SQL UPDATE Statement

What Does SQL UPDATE Do?

The UPDATE statement modifies existing data in a table. You can update one row, many rows, or even all rows — but watch out! A missing WHERE clause can cause mass updates by accident.

Basic UPDATE Syntax

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

Update a Single Record

-- Update a user's email
UPDATE Users
SET email = 'new_email@example.com'
WHERE user_id = 101;

Update Multiple Columns

-- Update username and email together
UPDATE Users
SET 
  username = 'new_username',
  email = 'new_email@toktuk.com'
WHERE user_id = 102;

Update All Rows (Use With Caution)

-- Set all videos to 0 views (careful!)
UPDATE Videos
SET views = 0;

⚠️ This affects every row. Always back up your data or wrap in a transaction when unsure.

Best Practices for UPDATE

Always include a WHERE clause unless you're intentionally updating everything
Preview affected rows first with a SELECT using the same condition
Use transactions when updating multiple related tables
Keep an audit trail of changes when possible
Validate values before updating (especially for types like dates, emails, enums)

SQL Learning

SQL Learning

SQL UPDATE Statement

What Does SQL UPDATE Do?

Basic UPDATE Syntax

Update a Single Record

Update Multiple Columns

Update All Rows (Use With Caution)

Best Practices for UPDATE

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Related Topics

Data Modification Overview

INSERT Statement

DELETE Statement