What happens if a DELETE statement has no WHERE clause?

All rows in the table are deleted

The statement is silently ignored

Only duplicate rows are deleted

After DELETE FROM table_name; runs with no WHERE, what remains?

An empty table with its structure intact

The table itself is dropped entirely

The table structure is also deleted

Which statement correctly deletes only rows matching a condition?

DELETE FROM Customers WHERE Country = 'Spain';

DELETE Customers SET Country = 'Spain';

DELETE * FROM Customers WHERE Country = 'Spain';

How does DELETE differ from TRUNCATE when clearing a table?

DELETE can use WHERE for specific rows; TRUNCATE removes all rows

DELETE removes the table itself; TRUNCATE keeps it

TRUNCATE can filter rows with WHERE; DELETE cannot

SQL Delete

The DELETE statement removes existing rows from a table.

Removing rows with DELETE

The DELETE statement removes whole rows from a table. You name the table and use a WHERE clause to say which rows should go. DELETE always removes entire rows; if you only want to clear a single field, you use UPDATE to set that field to NULL instead.

Deleting specific rows

-- Remove one employee by id
DELETE FROM Employees
WHERE employee_id = 101;

-- Remove every employee in a closed department
DELETE FROM Employees
WHERE department = 'Legacy';

Note: A DELETE with no WHERE clause removes every row in the table. DELETE FROM Employees; empties the entire table. Confirm your WHERE clause is present and correct before running the statement.

The WHERE clause controls the damage

Just as with UPDATE, the WHERE clause is what limits a delete to the rows you actually mean to remove. A precise condition removes one row, a broad condition removes many, and no condition removes them all. Because deleted rows are gone, it pays to be careful here.

WHERE clause	Rows removed
WHERE employee_id = 101	One specific row
WHERE department = 'Legacy'	Every row in that department
WHERE salary IS NULL	Every row missing a salary
(no WHERE clause)	All rows in the table

A safe way to preview a delete

Before running a delete, it is a good habit to run a SELECT with the same WHERE clause first. Whatever rows that SELECT returns are exactly the rows the DELETE will remove. This lets you confirm your condition targets the right data before anything is lost.

Preview, then delete

-- 1. See which rows match
SELECT * FROM Employees
WHERE department = 'Legacy';

-- 2. If the list looks right, remove them
DELETE FROM Employees
WHERE department = 'Legacy';

DELETE compared with DROP and TRUNCATE

It helps to know how DELETE differs from two related commands. DELETE removes rows but keeps the table itself, and it can be filtered with WHERE. TRUNCATE quickly removes all rows but keeps the empty table. DROP removes the table structure entirely.

DELETE removes whole rows and leaves the table in place.
TRUNCATE empties all rows at once but keeps the table.
DROP TABLE removes the table and its structure completely.
To clear a single field instead of a row, use UPDATE ... SET column = NULL.

Note: Where your database supports transactions, wrapping a delete in a transaction lets you roll back if the result is not what you expected. Previewing with SELECT first is still the simplest safeguard.

Exercise: SQL Delete

What does the DELETE statement do?

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