5.3 Inserting Data Using Connector/Python

Inserting or updating data is also done using the handler structure known as a cursor. When you use a transactional storage engine such as InnoDB (the default in MySQL 5.5 and later), you must commit the data after a sequence of INSERT, DELETE, and UPDATE statements.

This example shows how to insert new data. The second INSERT depends on the value of the newly created primary key of the first. The example also demonstrates how to use extended formats. The task is to add a new employee starting to work tomorrow with a salary set to 50000.

Note

The following example uses tables created in the example Section 5.2, “Creating Tables Using Connector/Python”. The AUTO_INCREMENT column option for the primary key of the employees table is important to ensure reliable, easily searchable data.

from __future__ import print_function
from datetime import date, datetime, timedelta
import mysql.connector

cnx = mysql.connector.connect(user='scott', database='employees')
cursor = cnx.cursor()

tomorrow = datetime.now().date() + timedelta(days=1)

add_employee = ("INSERT INTO employees "
               "(first_name, last_name, hire_date, gender, birth_date) "
               "VALUES (%s, %s, %s, %s, %s)")
add_salary = ("INSERT INTO salaries "
              "(emp_no, salary, from_date, to_date) "
              "VALUES (%(emp_no)s, %(salary)s, %(from_date)s, %(to_date)s)")

data_employee = ('Geert', 'Vanderkelen', tomorrow, 'M', date(1977, 6, 14))

# Insert new employee
cursor.execute(add_employee, data_employee)
emp_no = cursor.lastrowid

# Insert salary information
data_salary = {
  'emp_no': emp_no,
  'salary': 50000,
  'from_date': tomorrow,
  'to_date': date(9999, 1, 1),
}
cursor.execute(add_salary, data_salary)

# Make sure data is committed to the database
cnx.commit()

cursor.close()
cnx.close()

We first open a connection to the MySQL server and store the connection object in the variable cnx. We then create a new cursor, by default a MySQLCursor object, using the connection's cursor() method.

We could calculate tomorrow by calling a database function, but for clarity we do it in Python using the datetime module.

Both INSERT statements are stored in the variables called add_employee and add_salary. Note that the second INSERT statement uses extended Python format codes.

The information of the new employee is stored in the tuple data_employee. The query to insert the new employee is executed and we retrieve the newly inserted value for the emp_no column (an AUTO_INCREMENT column) using the lastrowid property of the cursor object.

Next, we insert the new salary for the new employee, using the emp_no variable in the dictionary holding the data. This dictionary is passed to the execute() method of the cursor object if an error occurred.

Since by default Connector/Python turns autocommit off, and MySQL 5.5 and later uses transactional InnoDB tables by default, it is necessary to commit your changes using the connection's commit() method. You could also roll back using the rollback() method.