MySQL Update

Update Table

You can update existing records in a table by using the "UPDATE" statement:

Example

import mysql.connector

mydb = mysql.connector.connect(
  host="localhost",

user="yourusername",
  password="yourpassword",
  database="mydatabase"
)

mycursor =
mydb.cursor()

sql = "UPDATE customers SET address = 'Canyon 123'
WHERE address = 'Valley 345'"

mycursor.execute(sql)

mydb.commit()

print(mycursor.rowcount, "record(s) affected")

Note: Important!: Notice the statement: mydb.commit(). It is required to make the changes, otherwise no changes are made to the table.

Note: Notice the WHERE clause in the UPDATE syntax: The WHERE clause specifies which record or records that should be updated. If you omit the WHERE clause, all records will be updated!

Prevent SQL Injection

It is considered a good practice to escape the values of any query, also in update statements.

This is to prevent SQL injections, which is a common web hacking technique to destroy or misuse your database.

The mysql.connector module uses the placeholder %s to escape values in the update statement:

Example

import mysql.connector

mydb = mysql.connector.connect(
  host="localhost",

user="yourusername",
  password="yourpassword",
  database="mydatabase"
)

mycursor = mydb.cursor()

sql = "UPDATE customers SET address = %s
WHERE address = %s"
val = ("Valley 345", "Canyon 123")

mycursor.execute(sql,
val)

mydb.commit()

print(mycursor.rowcount, "record(s)
affected")