Why UPDATE needs caution in SQL - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to update the salary of employees in the 'employees' table.

SQL

UPDATE employees SET salary = salary [1] 1000 WHERE department = 'Sales';

Drag options to blanks, or click blank then click option'

A+

B/

C*

D-

Attempts:

3 left

💡 Hint

Common Mistakes

Using '-' will decrease the salary instead of increasing it.

Using '*' or '/' will multiply or divide the salary, which is not intended here.

The '+' operator increases the salary by 1000 for employees in the Sales department.

2fill in blank

medium

Complete the code to update the status of orders to 'shipped' only for orders with status 'pending'.

SQL

UPDATE orders SET status = 'shipped' WHERE status [1] 'pending';

Drag options to blanks, or click blank then click option'

A>

B=

C!=

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using '!=' will update orders that are not pending, which is incorrect.

Using '>' or '<' does not make sense for string comparison here.

The '=' operator selects orders where the status is exactly 'pending' to update them to 'shipped'.

3fill in blank

hard

Fix the error in the UPDATE statement that tries to set all product prices to 0 but accidentally omits the WHERE clause.

SQL

UPDATE products SET price = [1];

Drag options to blanks, or click blank then click option'

ANULL

B''

C0

D-1

Attempts:

3 left

💡 Hint

Common Mistakes

Using NULL or empty string may cause errors or unexpected results.

Forgetting the WHERE clause can update all rows unintentionally.

Setting price to 0 is valid, but omitting WHERE updates all rows. Use caution to avoid unintended mass updates.

4fill in blank

hard

Fill both blanks to update the 'quantity' by subtracting 1 only for items where quantity is greater than 0.

SQL

UPDATE inventory SET quantity = quantity [1] 1 WHERE quantity [2] 0;

Drag options to blanks, or click blank then click option'

A-

B+

C>

D<=

Attempts:

3 left

💡 Hint

Common Mistakes

Adding 1 instead of subtracting changes the quantity incorrectly.

Using '<=' allows zero or negative quantities, which may be invalid.

Subtract 1 from quantity only if quantity is greater than 0 to avoid negative values.

5fill in blank

hard

Fill all three blanks to update the 'status' to 'inactive' and set 'last_updated' to current date only for users with 'active' status and last login before 2023-01-01.

SQL

UPDATE users SET status = [1], last_updated = [2] WHERE status = [3] AND last_login < '2023-01-01';

Drag options to blanks, or click blank then click option'

A'inactive'

BCURRENT_DATE

C'active'

D'2023-01-01'

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong status values or missing quotes causes errors.

Not filtering by status or last_login can update unintended users.

This updates only active users who last logged in before 2023-01-01, setting their status to inactive and recording the update date.