UPDATE with WHERE condition in SQL - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the UPDATE statement do in SQL?

The UPDATE statement changes existing data in a table by modifying one or more columns for rows that match a condition.

beginner

Why is the WHERE clause important in an UPDATE statement?

The WHERE clause limits which rows get updated. Without it, all rows in the table will be changed.

beginner

Write the basic syntax of an UPDATE statement with a WHERE condition.

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

intermediate

What happens if you run UPDATE employees SET salary = 5000; without a WHERE clause?

All rows in the employees table will have their salary set to 5000, which might not be what you want.

beginner

How can you update only the rows where the employee's department is 'Sales'?

Use a WHERE clause to specify the condition: <br>

UPDATE employees SET salary = 6000 WHERE department = 'Sales';

What does the WHERE clause do in an UPDATE statement?

A Deletes rows from the table

B Specifies new column names

C Creates a new table

D Limits which rows are updated

The WHERE clause filters rows so only matching rows get updated.

What happens if you omit the WHERE clause in an UPDATE statement?

A All rows in the table are updated

B No rows are updated

C Only one row is updated

D The table is deleted

Without WHERE, the update applies to every row in the table.

Which SQL keyword is used to specify the new values in an UPDATE statement?

A WHERE

B FROM

C SET

D SELECT

The SET keyword defines the columns and their new values.

How would you update the 'status' column to 'active' only for users with 'id' 10?

A SELECT status FROM users WHERE id = 10;

B UPDATE users SET status = 'active' WHERE id = 10;

C UPDATE users SET status = 'active';

D UPDATE users WHERE id = 10 SET status = 'active';

The correct syntax places SET before WHERE.

Which of these is a valid UPDATE statement?

A UPDATE products SET price = 20 WHERE id = 5;

B UPDATE products price = 20 WHERE id = 5;

C UPDATE products SET price 20 WHERE id = 5;

D UPDATE products WHERE id = 5 SET price = 20;

Option A uses correct syntax: UPDATE table SET column = value WHERE condition;

Explain how the UPDATE statement works with a WHERE condition in SQL.

Think about how you tell SQL which rows to change and what to change.

Describe what could happen if you forget the WHERE clause in an UPDATE statement.

Imagine changing every item in a list by mistake.