Sams Teach Yourself MySQL in 21 Days, Second Edition

Performing Updates

With the UPDATE command, you can modify the values of existing data in a table. The format for the statement is as follows:

UPDATE [LOW PRIORITY] [IGNORE] table_name
  SET column_name1=expression1, column_name2=expression2,...
  [WHERE where_definition]
  [LIMIT num]

There are basically two parts to the query: the SET portion, to declare which column to set to what value; and the WHERE portion, which defines which rows are affected.

Let's practice using CREATE and INSERT again to create a temporary table called products and populate it with some data:

mysql> CREATE TEMPORARY TABLE products
    -> (product_name VARCHAR(20), price FLOAT(9,2));

mysql> INSERT INTO products
    -> VALUES ('Green sweater', 10.00),
    -> ('Brown jacket', 12.00); ...