Python PostgreSQL - Updating Tables

Updating a table in a PostgreSQL database using Python is a straightforward process. In this tutorial, we will cover the steps to update an existing record in a PostgreSQL table using the psycopg library.

Prerequisites

Before proceeding with this tutorial, ensure that you have the following prerequisites in place:

• PostgreSQL installed on your system
• Python 3.x installed on your system
• psycopg2 library installed on your system

Connecting to the PostgreSQL Database

The first step is to establish a connection to the PostgreSQL database. Use the following code snippet to create a connection:

import psycopg2
conn = psycopg2.connect(
    host="hostname",
    database="database_name",
    user="username",
    password="password"
)

Update the host, database_name, username, and password variables with your database details.

Updating a Table

Once connected to the database, you can update an existing record by executing an SQL statement. The UPDATE statement is used to modify existing records in a table.

cur = conn.cursor()
cur.execute(
    """
    UPDATE table_name
    SET column1 = value1,
        column2 = value2,
        column3 = value3
    WHERE id = record_id;
    """
)

In the above code, replace table_name, column1, column2, and column3 with the relevant table and column names, and replace value1, value2, and value3 with the new values for each column. Also, replace record_id variable with the ID of the record to be updated.

Once the update statement is executed, the record in the table will be modified.

Committing the Changes

After the update statement is executed, the changes will not be saved to the database until you commit them. Use the following code snippet to commit the changes:

conn.commit()

Closing the Connection

After completing the update operation, close the database connection using the following code snippet:

cur.close()
conn.close()

Conclusion

In this tutorial, we have covered the steps to update an existing record in a PostgreSQL table using Python. By following the steps outlined in this tutorial, you can successfully update records in your PostgreSQL database using Python and psycopg2 library.