UPDATE multiple columns in SQL - Cheat Sheet & Quick Revision

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What does the SQL UPDATE statement do?

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

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How do you update multiple columns in a single SQL UPDATE statement?

You list each column and its new value separated by commas after the SET keyword, like: SET column1 = value1, column2 = value2.

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Why should you always include a WHERE clause in an UPDATE statement?

Without a WHERE clause, the UPDATE will change all rows in the table, which might cause unintended data loss or errors.

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Example: Update the 'name' to 'Alice' and 'age' to 30 for the user with id 5. Write the SQL query.

UPDATE users SET name = 'Alice', age = 30 WHERE id = 5;

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Can you update columns to NULL using UPDATE? How?

Yes, you can set a column to NULL by assigning NULL as the value, for example: SET column_name = NULL.

Which keyword is used to specify the columns to update in an SQL UPDATE statement?

A FROM

B SET

C WHERE

D SELECT

The SET keyword is used to list the columns and their new values in an UPDATE statement.

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

A The query will fail

B No rows are updated

C Only one row is updated

D All rows in the table are updated

Without a WHERE clause, the UPDATE affects every row in the table.

How do you update two columns 'price' and 'stock' in one UPDATE statement?

A SET price = 10, stock = 5

B SET price = 10 AND stock = 5

C WHERE price = 10, stock = 5

D UPDATE price = 10, stock = 5

Multiple columns are updated by separating assignments with commas after SET.

Which of these is a valid UPDATE statement to change 'status' to 'active' and 'score' to 100 for user_id 7?

A UPDATE users SET status = 'active', score = 100 WHERE user_id = 7;

B UPDATE users SET status = 'active' AND score = 100 WHERE user_id = 7;

C UPDATE users WHERE user_id = 7 SET status = 'active', score = 100;

D UPDATE users SET status = 'active' score = 100 WHERE user_id = 7;

The correct syntax uses commas to separate column assignments after SET.

Can you update a column to NULL in SQL?

A Only if the column is a number

B No, NULL is not allowed in UPDATE

C Yes, by setting column = NULL

D Only if the column is a string

You can set any column to NULL by assigning NULL in the UPDATE statement.

Explain how to update multiple columns in a SQL table and why the WHERE clause is important.

Think about changing more than one detail at once and controlling which rows change.

Write an example SQL UPDATE statement that changes two columns for a specific row.

Use a simple table like users and columns like name and age.