MySQL UPDATE Statement

The MySQL UPDATE Statement

The UPDATE statement is used to modify the existing records in a table.

UPDATE Syntax

UPDATE table_name
SET column1 = value1, column2 = value2, ...
WHERE condition; 

Note: Be careful when updating records in a table! Notice the WHERE clause in the UPDATE statement. The WHERE clause specifies which record(s) that should be updated. If you omit the WHERE clause, all records in the table will be updated!

Demo Database

Below is a selection from the “Customers” table in the Northwind sample database:

UPDATE Table

The following SQL statement updates the first customer (CustomerID = 1) with a new contact person and a new city.

Example

UPDATE Customers
SET ContactName = 'Alfred Schmidt', City = 'Frankfurt'
WHERE CustomerID = 1;

The selection from the “Customers” table will now look like this:

UPDATE Multiple Records

It is the WHERE clause that determines how many records will be updated.

The following SQL statement will update the PostalCode to 00000 for all records where country is “Mexico”:

Example

UPDATE Customers
SET PostalCode = 00000
WHERE Country = 'Mexico';

The selection from the “Customers” table will now look like this:

Update Warning!

Be careful when updating records. If you omit the WHERE clause, ALL records will be updated!

Example

UPDATE Customers
SET PostalCode = 00000;

The selection from the “Customers” table will now look like this: