How to Export a PostgreSQL Query to CSV

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By squashlabs, Last Updated: October 30, 2023

How to Export a PostgreSQL Query to CSV

Exporting PostgreSQL query results to CSV is a common task in database management. CSV (Comma-Separated Values) is a file format that stores tabular data in plain text, where each line represents a row and each value within a row is separated by a comma. This format is widely supported and can be easily imported into various applications such as spreadsheets, databases, and data analysis tools.

There are multiple ways to export PostgreSQL query results to CSV, depending on the tools and programming languages you are using. In this article, we will explore various methods to accomplish this task. We will cover exporting PostgreSQL query results to CSV using the command line, pgAdmin, and different programming languages such as Python, Java, PHP, Ruby, Node.js, .NET, Perl, Bash, Go, Rust, C++, PowerShell, R, Scala, Julia, Swift, Kotlin, Groovy, Lua, TypeScript, PowerShell Core, Objective-C, Erlang, OCaml, Perl 6, Crystal, Scheme, CoffeeScript, and Visual Basic.

Let’s dive into each method and see how to export PostgreSQL query results to CSV using different tools and programming languages.

Exporting PostgreSQL Query Result to CSV Using Command Line

The command line provides a simple and straightforward way to export PostgreSQL query results to CSV. PostgreSQL provides the psql command-line tool, which allows us to interact with the database and execute queries. We can use the -c option to specify the query we want to execute and the -o option to redirect the output to a file.

Here’s an example of how to export a PostgreSQL query result to CSV using the command line:

psql -c "COPY (SELECT * FROM table_name) TO '/path/to/output.csv' CSV HEADER"

In this example, we use the COPY command with a subquery to select the data we want to export. The TO clause specifies the output file path, and the CSV option indicates that we want to export the data in CSV format. The HEADER option includes a header row with the column names in the output file.

You can modify the query inside the COPY command to select the specific columns or add any additional filtering or sorting criteria as needed.

Related Article: Updating JSONB Columns in PostgreSQL

Exporting PostgreSQL Query Result to CSV Using pgAdmin

pgAdmin is a popular open-source administration and development platform for PostgreSQL. It provides an intuitive graphical user interface that allows us to manage databases, execute queries, and perform various database-related tasks.

To export a PostgreSQL query result to CSV using pgAdmin, follow these steps:

1. Open pgAdmin and connect to your PostgreSQL database.
2. In the object browser, navigate to the schema and table you want to export data from.
3. Right-click on the table and select “Query Tool” to open the query editor.
4. Write your query in the editor.
5. Click the “Execute” button to execute the query and view the result.
6. Right-click on the query result grid and select “Save As”.
7. Choose the CSV format and specify the output file path.
8. Click “Save” to export the query result to CSV.

pgAdmin provides a convenient way to execute queries and export the results to CSV directly from its graphical user interface. You can also save the query for future use or modify it as needed.

Exporting to CSV Using Python

Python is a popular programming language for data analysis and manipulation. It provides various libraries and modules that make it easy to work with databases, including PostgreSQL. We can use the psycopg2 library in Python to connect to a PostgreSQL database and execute queries.

Here’s an example of how to export a PostgreSQL query result to CSV using Python:

import psycopg2
import csv

# Connect to the PostgreSQL database
conn = psycopg2.connect(
    host="your_host",
    database="your_database",
    user="your_user",
    password="your_password"
)

# Create a cursor object to execute queries
cursor = conn.cursor()

# Execute the query
cursor.execute("SELECT * FROM table_name")

# Fetch all rows from the query result
rows = cursor.fetchall()

# Specify the output file path
output_file = "/path/to/output.csv"

# Write the query result to CSV
with open(output_file, "w", newline="") as file:
    writer = csv.writer(file)
    writer.writerow([desc[0] for desc in cursor.description])  # Write column names
    writer.writerows(rows)  # Write rows

# Close the cursor and connection
cursor.close()
conn.close()

In this example, we first import the necessary modules: psycopg2 for connecting to the PostgreSQL database and executing queries, and csv for writing the query result to CSV.

Next, we establish a connection to the PostgreSQL database using the psycopg2.connect() function. Make sure to provide the correct host, database, user, and password parameters.

We create a cursor object using the conn.cursor() method, which allows us to execute queries.

We execute the query using the cursor.execute() method. In this example, we select all rows from the “table_name” table.

We fetch all rows from the query result using the cursor.fetchall() method.

We specify the output file path where we want to save the CSV file.

Finally, we use the csv.writer object to write the query result to CSV. We first write the column names by extracting them from cursor.description, and then write the rows using the writer.writerows() method.

Make sure to close the cursor and connection using the cursor.close() and conn.close() methods after you are done.

You can modify the query to select specific columns or add any additional filtering or sorting criteria as needed.

Exporting to CSV Using JDBC

JDBC (Java Database Connectivity) is a Java API that allows Java programs to interact with databases. It provides a standard set of interfaces and classes for connecting to databases, executing queries, and retrieving results.

To export a PostgreSQL query result to CSV using JDBC, follow these steps:

1. Set up a JDBC connection to the PostgreSQL database. Make sure you have the PostgreSQL JDBC driver (e.g., postgresql.jar) in your classpath.
2. Create a Connection object using the DriverManager.getConnection() method. Provide the correct connection URL, username, and password.
3. Create a Statement object using the connection.createStatement() method.
4. Execute the query using the Statement.executeQuery() method.
5. Iterate over the query result using the ResultSet object.
6. Write the query result to CSV using a CSV writer library or by manually formatting the data.
7. Close the ResultSet, Statement, and Connection objects.

Here’s an example of how to export a PostgreSQL query result to CSV using JDBC in Java:

import java.io.FileWriter;
import java.io.IOException;
import java.sql.*;

public class ExportToCsvExample {
    public static void main(String[] args) {
        String jdbcUrl = "jdbc:postgresql://your_host:your_port/your_database";
        String username = "your_username";
        String password = "your_password";
        String query = "SELECT * FROM table_name";
        String outputCsvFile = "/path/to/output.csv";

        try (Connection connection = DriverManager.getConnection(jdbcUrl, username, password);
             Statement statement = connection.createStatement();
             ResultSet resultSet = statement.executeQuery(query);
             FileWriter fileWriter = new FileWriter(outputCsvFile)) {

            ResultSetMetaData metaData = resultSet.getMetaData();
            int columnCount = metaData.getColumnCount();

            // Write column names to CSV
            for (int i = 1; i <= columnCount; i++) {
                String columnName = metaData.getColumnName(i);
                fileWriter.append(columnName);
                if (i < columnCount) {
                    fileWriter.append(",");
                }
            }
            fileWriter.append("\n");

            // Write rows to CSV
            while (resultSet.next()) {
                for (int i = 1; i <= columnCount; i++) {
                    Object value = resultSet.getObject(i);
                    fileWriter.append(value != null ? value.toString() : "");
                    if (i < columnCount) {
                        fileWriter.append(",");
                    }
                }
                fileWriter.append("\n");
            }

            System.out.println("Exported query result to CSV successfully.");

        } catch (SQLException | IOException e) {
            e.printStackTrace();
        }
    }
}

In this example, we first define the JDBC URL, username, password, query, and output CSV file path. Make sure to replace the placeholders with the actual values.

We establish a connection to the PostgreSQL database using the DriverManager.getConnection() method.

We create a Statement object using the connection.createStatement() method.

We execute the query and obtain a ResultSet using the statement.executeQuery() method.

We get the metadata of the result set using the resultSet.getMetaData() method. This allows us to retrieve information about the columns in the result set.

We use a FileWriter to write the query result to the output CSV file. We first write the column names by iterating over the metadata and extracting the column names using the metaData.getColumnName() method. We then write the rows by iterating over the result set and retrieving the values using the resultSet.getObject() method.

Finally, we close the result set, statement, and connection using the try-with-resources statement.

You can modify the query to select specific columns or add any additional filtering or sorting criteria as needed.

Related Article: Processing Array_Agg Data in JSON Format in PostgreSQL

Exporting to CSV Using PHP

PHP is a popular server-side scripting language for web development. It provides various libraries and extensions for interacting with databases, including PostgreSQL. We can use the pg_query() function in PHP to execute queries and retrieve results from PostgreSQL.

To export a PostgreSQL query result to CSV using PHP, follow these steps:

1. Set up a connection to the PostgreSQL database using the pg_connect() function. Provide the correct host, database, username, and password parameters.
2. Execute the query using the pg_query() function.
3. Fetch all rows from the query result using the pg_fetch_all() function.
4. Specify the output file path where you want to save the CSV file.
5. Open the output file in write mode using the fopen() function.
6. Write the column names to the CSV file using the fputcsv() function.
7. Iterate over the rows and write each row to the CSV file using the fputcsv() function.
8. Close the output file using the fclose() function.

Here’s an example of how to export a PostgreSQL query result to CSV using PHP:

<?php
// Set up a connection to the PostgreSQL database
$conn = pg_connect("host=your_host dbname=your_database user=your_user password=your_password");

// Execute the query
$result = pg_query($conn, "SELECT * FROM table_name");

// Fetch all rows from the query result
$rows = pg_fetch_all($result);

// Specify the output file path
$outputFile = "/path/to/output.csv";

// Open the output file in write mode
$file = fopen($outputFile, "w");

// Write the column names to the CSV file
$columnNames = array_keys($rows[0]);
fputcsv($file, $columnNames);

// Write each row to the CSV file
foreach ($rows as $row) {
    fputcsv($file, $row);
}

// Close the output file
fclose($file);

// Close the database connection
pg_close($conn);

echo "Exported query result to CSV successfully.";
?>

In this example, we first set up a connection to the PostgreSQL database using the pg_connect() function. Make sure to provide the correct host, database, username, and password parameters.

We execute the query using the pg_query() function and obtain the result resource.

We fetch all rows from the query result using the pg_fetch_all() function. This returns an array of associative arrays, where each associative array represents a row.

We specify the output file path where we want to save the CSV file.

We open the output file in write mode using the fopen() function.

We write the column names to the CSV file by extracting them from the first row and using the fputcsv() function.

We iterate over the rows and write each row to the CSV file using the fputcsv() function.

Finally, we close the output file using the fclose() function and close the database connection using the pg_close() function.

You can modify the query to select specific columns or add any additional filtering or sorting criteria as needed.

Exporting to CSV Using Ruby

Ruby is a dynamic, object-oriented scripting language known for its simplicity and readability. It provides libraries and gems for interacting with databases, including PostgreSQL. We can use the pg gem in Ruby to connect to a PostgreSQL database and execute queries.

To export a PostgreSQL query result to CSV using Ruby, follow these steps:

1. Install the pg gem if you haven’t already done so by running gem install pg in your terminal.
2. Require the pg gem in your Ruby script.
3. Set up a connection to the PostgreSQL database using the PG::Connection.new method. Provide the correct host, port, database, username, and password parameters.
4. Execute the query using the connection.exec method.
5. Fetch all rows from the query result using the result.values method.
6. Specify the output file path where you want to save the CSV file.
7. Open the output file in write mode using the File.open method.
8. Write the column names to the CSV file.
9. Iterate over the rows and write each row to the CSV file.
10. Close the output file.

Here’s an example of how to export a PostgreSQL query result to CSV using Ruby:

require 'pg'
require 'csv'

# Set up a connection to the PostgreSQL database
connection = PG::Connection.new(
  host: 'your_host',
  port: 'your_port',
  dbname: 'your_database',
  user: 'your_user',
  password: 'your_password'
)

# Execute the query
result = connection.exec('SELECT * FROM table_name')

# Fetch all rows from the query result
rows = result.values

# Specify the output file path
output_file = '/path/to/output.csv'

# Write the query result to CSV
CSV.open(output_file, 'w') do |csv|
  csv << result.fields  # Write column names
  rows.each { |row| csv << row }  # Write rows
end

puts 'Exported query result to CSV successfully.'

# Close the connection
connection.close

In this example, we first require the pg gem and the csv module in Ruby.

We set up a connection to the PostgreSQL database using the PG::Connection.new method. Make sure to provide the correct host, port, database, username, and password parameters.

We execute the query using the connection.exec method and obtain the PG::Result object.

We fetch all rows from the query result using the result.values method. This returns an array of arrays, where each inner array represents a row.

We specify the output file path where we want to save the CSV file.

We open the output file in write mode using the File.open method.

We write the column names to the CSV file by accessing the result.fields property and using the << operator.

We iterate over the rows and write each row to the CSV file using the << operator.

Finally, we close the output file using the close method and close the database connection using the connection.close method.

You can modify the query to select specific columns or add any additional filtering or sorting criteria as needed.

Exporting to CSV Using Node.js

Node.js is a JavaScript runtime built on Chrome’s V8 JavaScript engine. It allows you to run JavaScript on the server-side and provides an event-driven, non-blocking I/O model that makes it lightweight and efficient. There are various libraries and modules available for working with databases in Node.js, including PostgreSQL. We can use the pg module in Node.js to connect to a PostgreSQL database and execute queries.

To export a PostgreSQL query result to CSV using Node.js, follow these steps:

1. Install the pg module if you haven’t already done so by running npm install pg in your terminal.
2. Require the pg module in your Node.js script.
3. Set up a connection to the PostgreSQL database using the pg.Pool class. Provide the correct connection parameters such as host, port, database, username, and password.
4. Execute the query using the pool.query method.
5. Fetch all rows from the query result using the result.rows property.
6. Specify the output file path where you want to save the CSV file.
7. Create a writable stream using the fs.createWriteStream method.
8. Write the column names to the CSV file.
9. Iterate over the rows and write each row to the CSV file.
10. Close the writable stream.

Here’s an example of how to export a PostgreSQL query result to CSV using Node.js:

const { Pool } = require('pg');
const fs = require('fs');
const csvWriter = require('csv-write-stream');

// Set up a connection pool to the PostgreSQL database
const pool = new Pool({
  user: 'your_user',
  host: 'your_host',
  database: 'your_database',
  password: 'your_password',
  port: 5432,
});

// Execute the query
pool.query('SELECT * FROM table_name', (error, result) => {
  if (error) {
    console.error('Error executing query:', error);
    return;
  }

  // Fetch all rows from the query result
  const rows = result.rows;

  // Specify the output file path
  const outputFile = '/path/to/output.csv';

  // Create a writable stream
  const writer = csvWriter();

  // Pipe the writable stream to the output file
  writer.pipe(fs.createWriteStream(outputFile));

  // Write the column names to the CSV file
  writer.write(Object.keys(rows[0]));

  // Write each row to the CSV file
  rows.forEach((row) => {
    writer.write(Object.values(row));
  });

  // Close the writable stream
  writer.end();

  console.log('Exported query result to CSV successfully.');

  // Release the connection from the pool
  pool.end();
});

In this example, we first require the pg, fs, and csv-write-stream modules in Node.js.

We set up a connection pool to the PostgreSQL database using the pg.Pool class. Make sure to provide the correct connection parameters such as host, port, database, username, and password.

We execute the query using the pool.query method and obtain the query result in the callback function.

We fetch all rows from the query result using the result.rows property.

We specify the output file path where we want to save the CSV file.

We create a writable stream using the csv-write-stream module and the fs.createWriteStream method.

We write the column names to the CSV file by accessing the keys of the first row and using the writer.write method.

We iterate over the rows and write each row to the CSV file by accessing the values of each row and using the writer.write method.

Finally, we close the writable stream using the writer.end method and release the connection from the pool using the pool.end method.

You can modify the query to select specific columns or add any additional filtering or sorting criteria as needed.

Exporting to CSV Using Java

Java is a popular programming language for building enterprise-scale applications. It provides a rich ecosystem of libraries and frameworks for working with databases, including PostgreSQL. We can use the JDBC (Java Database Connectivity) API in Java to connect to a PostgreSQL database and execute queries.

To export a PostgreSQL query result to CSV using Java, follow these steps:

1. Set up a JDBC connection to the PostgreSQL database. Make sure you have the PostgreSQL JDBC driver (e.g., postgresql.jar) in your classpath.
2. Create a Connection object using the DriverManager.getConnection() method. Provide the correct connection URL, username, and password.
3. Create a Statement object using the connection.createStatement() method.
4. Execute the query using the Statement.executeQuery() method.
5. Iterate over the query result using the ResultSet object.
6. Write the query result to CSV using a CSV writer library or by manually formatting the data.
7. Close the ResultSet, Statement, and Connection objects.

Here’s an example of how to export a PostgreSQL query result to CSV using JDBC in Java:

import java.io.FileWriter;
import java.io.IOException;
import java.sql.*;

public class ExportToCsvExample {
    public static void main(String[] args) {
        String jdbcUrl = "jdbc:postgresql://your_host:your_port/your_database";
        String username = "your_username";
        String password = "your_password";
        String query = "SELECT * FROM table_name";
        String outputCsvFile = "/path/to/output.csv";

        try (Connection connection = DriverManager.getConnection(jdbcUrl, username, password);
             Statement statement = connection.createStatement();
             ResultSet resultSet = statement.executeQuery(query);
             FileWriter fileWriter = new FileWriter(outputCsvFile)) {

            ResultSetMetaData metaData = resultSet.getMetaData();
            int columnCount = metaData.getColumnCount();

            // Write column names to CSV
            for (int i = 1; i <= columnCount; i++) {
                String columnName = metaData.getColumnName(i);
                fileWriter.append(columnName);
                if (i < columnCount) {
                    fileWriter.append(",");
                }
            }
            fileWriter.append("\n");

            // Write rows to CSV
            while (resultSet.next()) {
                for (int i = 1; i <= columnCount; i++) {
                    Object value = resultSet.getObject(i);
                    fileWriter.append(value != null ? value.toString() : "");
                    if (i < columnCount) {
                        fileWriter.append(",");
                    }
                }
                fileWriter.append("\n");
            }

            System.out.println("Exported query result to CSV successfully.");

        } catch (SQLException | IOException e) {
            e.printStackTrace();
        }
    }
}

In this example, we first define the JDBC URL, username, password, query, and output CSV file path. Make sure to replace the placeholders with the actual values.

We establish a connection to the PostgreSQL database using the DriverManager.getConnection() method.

We create a Statement object using the connection.createStatement() method.

We execute the query using the statement.executeQuery() method. In this example, we select all rows from the “table_name” table.

We fetch all rows from the query result using the resultSet.next() method.

We specify the output file path where we want to save the CSV file.

Finally, we use the fileWriter object to write the query result to CSV. We first write the column names by iterating over the metadata and extracting the column names using the metaData.getColumnName() method. We then write the rows by iterating over the result set and retrieving the values using the resultSet.getObject() method.

Make sure to close the resultSet, statement, and connection objects using the try-with-resources statement.

You can modify the query to select specific columns or add any additional filtering or sorting criteria as needed.

Exporting to CSV Using Perl

Perl is a high-level, general-purpose programming language known for its useful text processing capabilities. It provides various modules and libraries for working with databases, including PostgreSQL. We can use the DBI module in Perl to connect to a PostgreSQL database and execute queries.

To export a PostgreSQL query result to CSV using Perl, follow these steps:

1. Install the DBI and DBD::Pg modules if you haven’t already done so. You can install them via the CPAN shell or by running cpanm DBI DBD::Pg in your terminal.
2. Use the DBI module to connect to the PostgreSQL database. Provide the correct connection parameters such as host, port, database, username, and password.
3. Prepare and execute the query using the prepare() and execute() methods.
4. Fetch all rows from the query result using the fetchall_arrayref() method.
5. Specify the output file path where you want to save the CSV file.
6. Open the output file in write mode using the open() function.
7. Write the column names to the CSV file.
8. Iterate over the rows and write each row to the CSV file.
9. Close the output file.

Here’s an example of how to export a PostgreSQL query result to CSV using Perl:

use strict;
use warnings;
use DBI;

my $hostname = 'your_host';
my $port = 'your_port';
my $database = 'your_database';
my $username = 'your_username';
my $password = 'your_password';
my $query = 'SELECT * FROM table_name';
my $output_csv_file = '/path/to/output.csv';

# Connect to the PostgreSQL database
my $dbh = DBI->connect("dbi:Pg:dbname=$database;host=$hostname;port=$port", $username, $password)
  or die "Could not connect to database: $DBI::errstr";

# Prepare and execute the query
my $sth = $dbh->prepare($query);
$sth->execute();

# Fetch all rows from the query result
my $rows = $sth->fetchall_arrayref({});

# Specify the output file path
open(my $fh, '>', $output_csv_file) or die "Could not open file '$output_csv_file' for writing: $!";

# Write the column names to the CSV file
print $fh join(',', keys %{$rows->[0]}), "\n";

# Write each row to the CSV file
foreach my $row (@$rows) {
  print $fh join(',', map { defined $_ ? $_ : '' } values %$row), "\n";
}

# Close the output file
close($fh);

print "Exported query result to CSV successfully.\n";

# Disconnect from the database
$dbh->disconnect();

In this example, we first define the connection parameters, query, and output CSV file path. Make sure to replace the placeholders with the actual values.

We use the DBI module to connect to the PostgreSQL database using the connect() method.

We prepare the query using the prepare() method and execute it using the execute() method.

We fetch all rows from the query result using the fetchall_arrayref() method. This returns an array reference, where each element is a hash reference representing a row.

We specify the output file path where we want to save the CSV file.

We open the output file in write mode using the open() function.

We write the column names to the CSV file by joining the keys of the first row with commas using the join() function.

We iterate over the rows and write each row to the CSV file by joining the values of each row with commas using the join() function. We also handle any undefined values by replacing them with an empty string.

Finally, we close the output file using the close() function and disconnect from the database using the disconnect() method.

You can modify the query to select specific columns or add any additional filtering or sorting criteria as needed.

Exporting to CSV Using Bash

Bash is a popular Unix shell and command language that provides a useful scripting environment. It allows you to automate tasks and interact with various system utilities and programs. We can use the psql command-line tool in Bash to connect to a PostgreSQL database and execute queries.

To export a PostgreSQL query result to CSV using Bash, follow these steps:

1. Install the postgresql-client package if it is not already installed on your system.
2. Use the psql command-line tool to connect to the PostgreSQL database. Provide the correct connection parameters such as host, port, database, username, and password.
3. Execute the query and redirect the output to a file using the -c and -o options.
4. Specify the output file path where you want to save the CSV file.
5. Use the COPY command with a subquery to select the data you want to export. Use the TO clause to specify the output file path. Use the CSV option to indicate that you want to export the data in CSV format. Use the HEADER option to include a header row with the column names in the output file.

Here’s an example of how to export a PostgreSQL query result to CSV using Bash:

psql -h your_host -p your_port -d your_database -U your_user -c "COPY (SELECT * FROM table_name) TO '/path/to/output.csv' CSV HEADER"

In this example, we use the psql command-line tool with the following options:

– -h specifies the hostname of the PostgreSQL server.
– -p specifies the port number of the PostgreSQL server.
– -d specifies the name of the database.
– -U specifies the username for connecting to the database.
– -c allows us to specify the query to execute.
– -o allows us to redirect the output to a file.

We use the COPY command with a subquery to select all rows from the “table_name” table. We specify the output file path using the TO clause. We indicate that we want to export the data in CSV format using the CSV option. We include a header row with the column names in the output file using the HEADER option.

You can modify the query inside the COPY command to select specific columns or add any additional filtering or sorting criteria as needed.

Exporting to CSV Using Go

Go is a statically typed, compiled programming language designed for simplicity, efficiency, and readability. It provides standard libraries and packages for working with databases, including PostgreSQL. We can use the database/sql package in Go to connect to a PostgreSQL database and execute queries.

To export a PostgreSQL query result to CSV using Go, follow these steps:

1. Import the necessary packages in your Go code: database/sql, fmt, os, and github.com/lib/pq.
2. Set up a connection to the PostgreSQL database using the sql.Open() function. Provide the correct connection parameters such as host, port, database, username, and password.
3. Prepare and execute the query using the db.Query() or db.QueryRow() method.
4. Fetch all rows from the query result using the rows.Next() and rows.Scan() methods.
5. Specify the output file path where you want to save the CSV file.
6. Create a file for writing using the os.Create() function.
7. Write the column names to the CSV file.
8. Iterate over the rows and write each row to the CSV file.
9. Close the file and the database connection.

Here’s an example of how to export a PostgreSQL query result to CSV using Go:

package main

import (
	"database/sql"
	"fmt"
	"os"

	_ "github.com/lib/pq"
)

func main() {
	connStr := "host=your_host port=your_port dbname=your_database user=your_user password=your_password sslmode=disable"
	query := "SELECT * FROM table_name"
	outputCsvFile := "/path/to/output.csv"

	// Set up a connection to the PostgreSQL database
	db, err := sql.Open("postgres", connStr)
	if err != nil {
		fmt.Println("Error connecting to database:", err)
		return
	}
	defer db.Close()

	// Prepare and execute the query
	rows, err := db.Query(query)
	if err != nil {
		fmt.Println("Error executing query:", err)
		return
	}
	defer rows.Close()

	// Specify the output file path
	file, err := os.Create(outputCsvFile)
	if err != nil {
		fmt.Println("Error creating file:", err)
		return
	}
	defer file.Close()

	// Write the column names to the CSV file
	columns, err := rows.Columns()
	if err != nil {
		fmt.Println("Error getting column names:", err)
		return
	}
	file.WriteString(fmt.Sprintf("%s\n", columns))

	// Write each row to the CSV file
	values := make([]interface{}, len(columns))
	pointers := make([]interface{}, len(columns))
	for i := range values {
		pointers[i] = &values[i]
	}

	for rows.Next() {
		err := rows.Scan(pointers...)
		if err != nil {
			fmt.Println("Error scanning row:", err)
			return
		}

		var row string
		for _, value := range values {
			if value != nil {
				row += fmt.Sprintf("%v,", value)
			} else {
				row += ","
			}
		}
		file.WriteString(fmt.Sprintf("%s\n", row[:len(row)-1]))
	}

	fmt.Println("Exported query result to CSV successfully.")
}

In this example, we first define the connection string, query, and output CSV file path. Make sure to replace the placeholders with the actual values.

We set up a connection to the PostgreSQL database using the sql.Open() function and the "postgres" driver. We defer closing the database connection using the defer keyword to ensure it is closed at the end of the function.

We prepare and execute the query using the db.Query() method. We defer closing the query result using the defer keyword to ensure it is closed at the end of the function.

We specify the output file path where we want to save the CSV file.

We create a file for writing using the os.Create() function. We defer closing the file using the defer keyword to ensure it is closed at the end of the function.

We write the column names to the CSV file by retrieving them from the query result using the rows.Columns() method. We use the file.WriteString() method to write the column names to the file.

We iterate over the rows using the rows.Next() method. We scan each row into a slice of interface values using the rows.Scan() method and iterate over the values to construct a comma-separated string representing the row. We use the file.WriteString() method to write each row to the file.

Finally, we print a success message and return.

You can modify the query to select specific columns or add any additional filtering or sorting criteria as needed.

Exporting to CSV Using Rust

Rust is a modern, safe, and efficient systems programming language that guarantees memory safety and thread safety. It provides a useful type system and a growing ecosystem of libraries and frameworks. We can use the postgres crate in Rust to connect to a PostgreSQL database and execute queries.

To export a PostgreSQL query result to CSV using Rust, follow these steps:

1. Add the postgres crate as a dependency in your Cargo.toml file.
2. Use the postgres crate to connect to the PostgreSQL database. Provide the correct connection parameters such as host, port, database, username, and password.
3. Prepare and execute the query using the Connection::query() or Connection::query_iter() method.
4. Fetch all rows from the query result using the Row::get() method.
5. Specify the output file path where you want to save the CSV file.
6. Create a file for writing using the File::create() function.
7. Write the column names to the CSV file.
8. Iterate over the rows and write each row to the CSV file.
9. Close the file.

Here’s an example of how to export a PostgreSQL query result to CSV using Rust:

use postgres::{Client, NoTls};
use std::fs::File;
use std::io::Write;

fn main() {
    let conn_str = "host=your_host port=your_port dbname=your_database user=your_user password=your_password";
    let query = "SELECT * FROM table_name";
    let output_csv_file = "/path/to/output.csv";

    // Connect to the PostgreSQL database
    let mut client = Client::connect(conn_str, NoTls).expect("Failed to connect to database");

    // Execute the query
    let rows = client.query(query, &[]).expect("Failed to execute query");

    // Specify the output file path
    let mut file = File::create(output_csv_file).expect("Failed to create file");

    // Write the column names to the CSV file
    let columns: Vec<_> = rows.columns().into_iter().map(|c| c.name().to_owned()).collect();
    writeln!(&mut file, "{}", columns.join(",")).expect("Failed to write to file");

    // Write each row to the CSV file
    for row in rows {
        let values: Vec<String> = row
            .iter()
            .map(|value| match value {
                Some(v) => v.to_string(),
                None => "".to_string(),
            })
            .collect();
        writeln!(&mut file, "{}", values.join(",")).expect("Failed to write to file");
    }

    println!("Exported query result to CSV successfully.");
}

In this example, we first define the connection string, query, and output CSV file path. Make sure to replace the placeholders with the actual values.

We use the Client::connect() method from the postgres crate to connect to the PostgreSQL database. We expect the connection to succeed, otherwise we print an error message.

We execute the query using the Client::query() method and obtain a Row iterator. We expect the query execution to succeed, otherwise we print an error message.

We specify the output file path where we want to save the CSV file.

We create a file for writing using the File::create() function. We expect the file creation to succeed, otherwise we print an error message.

We write the column names to the CSV file by iterating over the columns using the Column::name() method and joining them with commas. We use the writeln!() macro with a mutable reference to the file to write the column names.

We iterate over the rows using the Row iterator. For each row, we iterate over the values using the iter() method, convert them to strings, and handle any None values by replacing them with an empty string. We join the values with commas and use the writeln!() macro to write each row to the file.

Finally, we print a success message.

You can modify the query to select specific columns or add any additional filtering or sorting criteria as needed.

Exporting to CSV Using C++

C++ is a general-purpose programming language known for its efficiency and performance. It provides a rich set of libraries and frameworks for various purposes, including database connectivity. We can use the libpqxx library in C++ to connect to a PostgreSQL database and execute queries.

To export a PostgreSQL query result to CSV using C++, follow these steps:

1. Install the libpqxx library if it is not already installed on your system.
2. Include the necessary headers in your C++ code: pqxx/pqxx for the libpqxx library and fstream for file handling.
3. Set up a connection to the PostgreSQL database using the pqxx::connection class. Provide the correct connection parameters such as host, port, database, username, and password.
4. Prepare and execute the query using the pqxx::work class.
5. Fetch all rows from the query result using the pqxx::result::const_iterator class.
6. Specify the output file path where you want to save the CSV file.
7. Open the output file in write mode using the std::ofstream class.
8. Write the column names to the CSV file.
9. Iterate over the rows and write each row to the CSV file.
10. Close the file.

Here’s an example of how to export a PostgreSQL query result to CSV using C++ and the libpqxx library:

#include <pqxx/pqxx>
#include <fstream>

int main() {
    std::string conn_str = "host=your_host port=your_port dbname=your_database user=your_user password=your_password";
    std::string query = "SELECT * FROM table_name";
    std::string output_csv_file = "/path/to/output.csv";

    // Set up a connection to the PostgreSQL database
    pqxx::connection conn(conn_str);

    // Prepare and execute the query
    pqxx::work txn(conn);
    pqxx::result result = txn.exec(query);

    // Specify the output file path
    std::ofstream file(output_csv_file);

    // Write the column names to the CSV file
    for (auto const& column : result.columns()) {
        file << column.name();
        if (&column != &result.columns().back()) {
            file << ",";
        }
    }
    file << std::endl;

    // Write each row to the CSV file
    for (auto const& row : result) {
        for (auto const& field : row) {
            file << field.c_str();
            if (&field != &row.back()) {
                file << ",";
            }
        }
        file << std::endl;
    }

    std::cout << "Exported query result to CSV successfully." << std::endl;

    return 0;
}

In this example, we first define the connection string, query, and output CSV file path. Make sure to replace the placeholders with the actual values.

We set up a connection to the PostgreSQL database using the pqxx::connection class. The connection is established and closed automatically using the constructor and destructor of the pqxx::connection class.

We prepare and execute the query using the pqxx::work class and the exec() method. The query is executed within a transaction to ensure consistency.

We specify the output file path where we want to save the CSV file.

We open the output file in write mode using the std::ofstream class.

We write the column names to the CSV file by iterating over the columns of the pqxx::result object and writing each column name to the file. We use the << operator to write to the file.

We iterate over the rows of the pqxx::result object and write each row to the CSV file. We iterate over the fields of each row and write each field value to the file. We use the << operator to write to the file.

Finally, we print a success message.

You can modify the query to select specific columns or add any additional filtering or sorting criteria as needed.

Exporting to CSV Using PowerShell

PowerShell is a task automation and configuration management framework developed by Microsoft. It provides a command-line shell and scripting language that allows you to automate administrative tasks and manage systems. We can use the psql command-line tool in PowerShell to connect to a PostgreSQL database and execute queries.

To export a PostgreSQL query result to CSV using PowerShell, follow these steps:

1. Install the postgresql-client package if it is not already installed on your system.
2. Use the psql command-line tool to connect to the PostgreSQL database. Provide the correct connection parameters such as host, port, database, username, and password.
3. Execute the query and redirect the output to a file using the -c and -o options.
4. Specify the output file path where you want to save the CSV file.
5. Use the COPY command with a subquery to select the data you want to export. Use the TO clause to specify the output file path. Use the CSV option to indicate that you want to export the data in CSV format. Use the HEADER option to include a header row with the column names in the output file.

Here’s an example of how to export a PostgreSQL query result to CSV using PowerShell:

psql -h your_host -p your_port -d your_database -U your_user -c "COPY (SELECT * FROM table_name) TO '/path/to/output.csv' CSV HEADER"

In this example, we use the psql command-line tool with the following options:

– -h specifies the hostname of the PostgreSQL server.
– -p specifies the port number of the PostgreSQL server.
– -d specifies the name of the database.
– -U specifies the username for connecting to the database.
– -c allows us to specify the query to execute.
– -o allows us to redirect the output to a file.

We use the COPY command with a subquery to select all rows from the “table_name” table. We specify the output file path using the TO clause. We indicate that we want to export the data in CSV format using the CSV option. We include a header row with the column names in the output file using the HEADER option.

You can modify the query inside the COPY command to select specific columns or add any additional filtering or sorting criteria as needed.

Exporting to CSV Using R

R is a programming language and environment for statistical computing and graphics. It provides a wide range of packages and functions for data manipulation, analysis, and visualization. We can use the RPostgreSQL package in R to connect to a PostgreSQL database and execute queries.

To export a PostgreSQL query result to CSV using R, follow these steps:

1. Install the RPostgreSQL package if it is not already installed. You can install it by running install.packages("RPostgreSQL") in your R console.
2. Load the RPostgreSQL package using the library() function.
3. Set up a connection to the PostgreSQL database using the dbConnect() function. Provide the correct connection parameters such as host, port, database, username, and password.
4. Execute the query using the dbGetQuery() function.
5. Fetch all rows from the query result using the fetch() function.
6. Specify the output file path where you want to save the CSV file.
7. Write the query result to CSV using the write.csv() function.

Here’s an example of how to export a PostgreSQL query result to CSV using R:

library(RPostgreSQL)

host <- "your_host"
port <- your_port
dbname <- "your_database"
user <- "your_user"
password <- "your_password"
query <- "SELECT * FROM table_name"
output_csv_file <- "/path/to/output.csv"

# Set up a connection to the PostgreSQL database
conn <- dbConnect(PostgreSQL(), host = host, port = port, dbname = dbname, user = user, password = password)

# Execute the query and fetch all rows
result <- dbGetQuery(conn, query)
rows <- fetch(result, n = -1)

# Specify the output file path and write to CSV
write.csv(rows, file = output_csv_file, row.names = FALSE)

cat("Exported query result to CSV successfully.\n")

# Disconnect from the database
dbDisconnect(conn)

In this example, we first define the connection parameters, query, and output CSV file path. Make sure to replace the placeholders with the actual values.

We load the RPostgreSQL package using the library() function.

We set up a connection to the PostgreSQL database using the dbConnect() function from the RPostgreSQL package. We specify the connection parameters and assign the connection object to the conn variable.

We execute the query using the dbGetQuery() function and obtain the query result as a data frame.

We fetch all rows from the query result using the fetch() function from the RPostgreSQL package. We specify n = -1 to fetch all rows.

We specify the output file path where we want to save the CSV file.

We write the query result to CSV using the write.csv() function. We specify the rows to write, the file path, and set row.names = FALSE to exclude the row names from the CSV file.

Finally, we print a success message and disconnect from the database using the dbDisconnect() function.

You can modify the query to select specific columns or add any additional filtering or sorting criteria as needed.

Exporting to CSV Using Scala

Scala is a general-purpose programming language that combines object-oriented programming and functional programming concepts. It runs on the Java Virtual Machine (JVM) and provides seamless interoperability with Java. We can use the scala-postgresql library in Scala to connect to a PostgreSQL database and execute queries.

To export a PostgreSQL query result to CSV using Scala, follow these steps:

1. Add the scala-postgresql library as a dependency in your build configuration file (e.g., build.sbt).
2. Import the necessary classes and objects in your Scala code: java.sql.DriverManager, java.io.FileWriter, and scala.collection.JavaConversions._.
3. Load the PostgreSQL JDBC driver using the Class.forName() method.
4. Set up a connection to the PostgreSQL database using the DriverManager.getConnection() method. Provide the correct connection parameters such as host, port, database, username, and password.
5. Create a statement object using the connection.createStatement() method.
6. Execute the query using the statement.executeQuery() method.
7. Fetch all rows from the query result using the ResultSet.next() and ResultSet.getString() methods.
8. Specify the output file path where you want to save the CSV file.
9. Open the output file in write mode using the FileWriter class.
10. Write the column names to the CSV file.
11. Iterate over the rows and write each row to the CSV file.
12. Close the output file.

Here’s an example of how to export a PostgreSQL query result to CSV using Scala and the scala-postgresql library:

import java.sql.DriverManager
import java.io.FileWriter
import scala.collection.JavaConversions._

object ExportToCsvExample extends App {
  val jdbcUrl = "jdbc:postgresql://your_host:your_port/your_database"
  val username = "your_username"
  val password = "your_password"
  val query = "SELECT * FROM table_name"
  val outputCsvFile = "/path/to/output.csv"

  // Load the PostgreSQL JDBC driver
  Class.forName("org.postgresql.Driver")

  // Set up a connection to the PostgreSQL database
  val connection = DriverManager.getConnection(jdbcUrl, username, password)

  // Create a statement object
  val statement = connection.createStatement()

  // Execute the query
  val resultSet = statement.executeQuery(query)

  // Specify the output file path
  val fileWriter = new FileWriter(outputCsvFile)

  // Write the column names to the CSV file
  val metadata = resultSet.getMetaData
  val columnCount = metadata.getColumnCount
  for (i <- 1 to columnCount) {
    fileWriter.append(metadata.getColumnName(i))
    if (i < columnCount) {
      fileWriter.append(",")
    }
  }
  fileWriter.append("\n")

  // Write each row to the CSV file
  while (resultSet.next()) {
    for (i <- 1 to columnCount) {
      val value = resultSet.getString(i)
      fileWriter.append(if (value != null) value else "")
      if (i < columnCount) {
        fileWriter.append(",")
      }
    }
    fileWriter.append("\n")
  }

  fileWriter.close()

  println("Exported query result to CSV successfully.")
}

In this example, we first define the JDBC URL, username, password, query, and output CSV file path. Make sure to replace the placeholders with the actual values.

We use the Class.forName() method to load the PostgreSQL JDBC driver.

We set up a connection to the PostgreSQL database using the DriverManager.getConnection() method. We provide the JDBC URL, username, and password.

We create a statement object using the connection.createStatement() method.

We execute the query using the statement.executeQuery() method and obtain a result set.

We specify the output file path where we want to save the CSV file.

We open the output file in write mode using the FileWriter class.

We write the column names to the CSV file by iterating over the metadata of the result set and extracting the column names using the metadata.getColumnName() method.

We iterate over the rows of the result set using the resultSet.next() method. For each row, we iterate over the columns and write each column value to the CSV file.

Finally, we close the output file and print a success message.

You can modify the query to select specific columns or add any additional filtering or sorting criteria as needed.

Additional Resources

– Export PostgreSQL query to CSV using psycopg2
– Export PostgreSQL query results to CSV in PHP
– Export PostgreSQL query to CSV in Python