Python - MySQL - Update data

In this tutorial we will learn to update data in MySQL database using Python.

We have covered how to insert data into MySQL table using Python and how to fetch data from MySQL table using Python in the previous tutorials. Feel free to check that out.

Prerequisite

To understand this tutorial you need to have some prior knowledge of MySQL.

Update table data

To update data from a table we have the following steps.

1. Connect to the MySQL server using the mysql.connector.connect() method.
2. Create MySQL cursor from the connection created in step 1.
3. Use the cursor to execute the UPDATE query.
4. Use the commit() method to save the changes.
5. Close connection.

In this tutorial we will be working with an employee table.

The table already has some rows which are shown below.

mysql< SELECT * FROM employee;
+------------+-----------+----------+---------------------+
| employeeid | firstname | lastname | created_at          |
+------------+-----------+----------+---------------------+
| e01        | John      | Doe      | 2018-01-01 10:20:30 |
| e02        | Jane      | Doe      | 2018-01-01 12:13:14 |
| e03        | Peter     | Parker   | 2018-01-02 15:16:17 |
| e04        | Bruce     | Banner   | 2018-01-03 10:20:30 |
| e05        | Bruce     | Wayne    | 2018-01-04 12:00:00 |
| e06        | Tony      | Stark    | 2018-01-05 12:13:14 |
| e07        | Doctor    | Strange  | 2018-01-05 13:14:15 |
| e08        | Doctor    | Who      | 2018-01-05 13:14:15 |
+------------+-----------+----------+---------------------+
8 rows in set (0.00 sec)

Update record

To update records in a table we take help of the execute() method and pass SQL query and the values that we want to update.

In the following Python program we are updating the firstname of the employee having id e08.

# import module
import mysql.connector

# import errorcode
from mysql.connector import errorcode

# get db connection
try:

    cnx = mysql.connector.connect(
        user='yusufshakeel',
        password='',
        host='127.0.0.1',
        database='mydb'
    )

except mysql.connector.Error as err:
    
    if err.errno == errorcode.ER_ACCESS_DENIED_ERROR:
        print('Invalid credential. Unable to access database.')
    elif err.errno == errorcode.ER_BAD_DB_ERROR:
        print('Database does not exists')
    else:
        print('Failed to connect to database')

# update data
try:
    # cursor
    cnxCursor = cnx.cursor()
    
    # placeholder
    firstname = "Dr."
    employeeid = "e08"
    
    # sql query
    query = "UPDATE employee SET firstname = %s WHERE employeeid = %s"
    
    # data
    data = (firstname, employeeid)
    
    # execute
    cnxCursor.execute(query, data)
    
    # commit
    cnx.commit()
    
    # total number of rows updated
    print("Total rows updated: %d" % cnxCursor.rowcount)
    
except mysql.connector.Error as err:
    
    print("Error:", err.message)

except:

    print("Unknown error occurred!")

finally:
    # close cursor
    cnxCursor.close()
    # close connection
    cnx.close()

On success the above code will give us the following output.

Total rows updated: 1

If we check the employeetable we will get the following output.

mysql> SELECT * FROM employee;
+------------+-----------+----------+---------------------+
| employeeid | firstname | lastname | created_at          |
+------------+-----------+----------+---------------------+
| e01        | John      | Doe      | 2018-01-01 10:20:30 |
| e02        | Jane      | Doe      | 2018-01-01 12:13:14 |
| e03        | Peter     | Parker   | 2018-01-02 15:16:17 |
| e04        | Bruce     | Banner   | 2018-01-03 10:20:30 |
| e05        | Bruce     | Wayne    | 2018-01-04 12:00:00 |
| e06        | Tony      | Stark    | 2018-01-05 12:13:14 |
| e07        | Doctor    | Strange  | 2018-01-05 13:14:15 |
| e08        | Dr.       | Who      | 2018-01-05 13:14:15 |
+------------+-----------+----------+---------------------+
8 rows in set (0.00 sec)