Python and MySQL - Exporting Data

Sometimes it can be useful to export data from a database, so that it can be analysed, or, to import in to another computer system. CSV, or Comma Separated Value files, are one such file format that allows for both of these scenarios.

Below is an example of how Python can be used to export data to a CSV file called ‘personexport.csv’, from a MySQL database table called ‘person’, which was used in the examples for selecting, inserting, updating, deleting and importing data.

Firstly, the CSV file path and name are set and a check is made to see if the path actually exists. If it does, a connection to the database is established and a query is executed to extract the data from the database. The CSV file is then opened for writing and the table headers, combined with the rows of data returned, are added to it.  Finally, confirmation of a successful export is provided. A ‘try-except-finally’ block is used to catch any errors that may occur, as well as close the database connection, regardless of whether the export is successful or not.

import csv
import os
import pymysql

# File path and name.
filePath = 'c:\\demo\\'
fileName = 'personexport.csv'

# Database connection variable.
connect = None

# Check if the file path exists.
if os.path.exists(filePath):


        # Connect to database.
        connect = pymysql.connect(host='localhost', db='testDB',
                                  user='testUN', passwd='testPW')

    except pymysql.DatabaseError as e:

        # Confirm unsuccessful connection and stop program execution.
        print("Database connection unsuccessful.")

    # Cursor to execute query.
    cursor = connect.cursor()

    # SQL to select data from the person table.
    sqlSelect = \
        "SELECT id, firstname, lastname, title, dob \
         FROM person \
         ORDER BY id"


        # Execute query.

        # Fetch the data returned.
        results = cursor.fetchall()

        # Extract the table headers.
        headers = [i[0] for i in cursor.description]

        # Add the table headers to the data returned.
        results = (tuple(headers),) + results

        # Open CSV file for writing.
        csvFile = csv.writer(open(filePath + fileName, 'w', newline=''),
                             delimiter=',', lineterminator='\r\n',
                             quoting=csv.QUOTE_ALL, escapechar='\\')

        # Add the headers and data to the CSV file.

        # Message stating export successful.
        print("Data export successful.")

    except pymysql.DatabaseError as e:

        # Message stating export unsuccessful.
        print("Data export unsuccessful.")


        # Close database connection.


    # Message stating file path does not exist.
    print("File path does not exist.")

The CSV file produced contains the following data.