UPDATE Statement

The UPDATE statement modifies existing rows in a table - changing one or more column values for records that match a given condition.

Basic Syntax

UPDATE customers
SET city = 'Gurugram'
WHERE customer_id = 1;

Updating Multiple Columns

UPDATE customers
SET city = 'Gurugram', email = 'riya@example.com'
WHERE customer_id = 1;

The Importance of WHERE

The WHERE clause determines which rows are affected. Leaving it out updates every single row in the table - one of the most common and costly mistakes when writing SQL.

-- Dangerous: updates ALL rows in the table!
UPDATE customers
SET city = 'Gurugram';