Why DELETE needs caution in SQL - Quick Recap

Recall & Review

beginner

What does the DELETE statement do in SQL?

DELETE removes rows from a table based on a condition. If no condition is given, it removes all rows.

beginner

Why should you be careful when using DELETE without a WHERE clause?

Because it deletes all rows in the table, which can cause data loss if done by mistake.

intermediate

How can DELETE affect related tables in a database?

If foreign keys with cascade delete are set, deleting rows can also remove related rows in other tables automatically.

beginner

What is a safe practice before running a DELETE query?

Run a SELECT query with the same WHERE condition first to check which rows will be deleted.

beginner

What can happen if you delete data without a backup?

You might lose important data permanently, making recovery difficult or impossible.

What happens if you run DELETE FROM table_name without a WHERE clause?

A All rows in the table are deleted

B Only the first row is deleted

C No rows are deleted

D An error occurs

Without a WHERE clause, DELETE removes every row in the table.

Which of the following is a good practice before deleting rows?

A Drop the entire table

B Delete without checking

C Run a SELECT query with the same condition

D Restart the database

Running a SELECT first helps confirm which rows will be deleted.

What does CASCADE DELETE do?

A Deletes related rows in other tables automatically

B Prevents any rows from being deleted

C Creates a backup before deleting

D Deletes only one row at a time

CASCADE DELETE removes related rows in tables linked by foreign keys.

Why is it risky to delete data without a backup?

A It slows down the database

B Data may be lost permanently

C It creates duplicate data

D It locks the table

Without backup, deleted data cannot be restored easily.

Which SQL command permanently removes rows from a table?

A SELECT

B INSERT

C UPDATE

D DELETE

DELETE removes rows permanently from a table.

Explain why you should be cautious when using the DELETE statement in SQL.

Think about what happens if you delete too much data by accident.

Describe safe steps to take before running a DELETE query.

How can you avoid deleting wrong data?