Structured query language (SQL): DELETE FROM table_name WHERE condition

The idea

This SQL statement removes rows from an existing table. DELETE FROM names the table whose rows will be removed; the WHERE clause then selects which rows qualify, for example DELETE FROM Students WHERE Year = 11 removes only Year 11 rows. Without WHERE, every row is deleted while the table structure remains. The statement does not remove the table itself, its columns or its definition, so the table still exists afterwards and can receive new rows. Learners should read each option carefully: a correct answer must name the table after FROM and give a condition that matches only the intended rows, and must not confuse row deletion with dropping a table or with changing stored values.

What earns the marks

• Identifies DELETE FROM as the clause that removes rows from the named table.
• Recognises that the WHERE clause restricts deletion to rows meeting the stated condition.
• Distinguishes deleting rows from deleting the table structure or its columns.
• Rejects an option that omits WHERE when only some rows should be removed, because all rows would be deleted.
• Confirms the table name follows FROM and the condition follows WHERE in the correct order.

Common mistakes and how to put them right

• Thinking DELETE removes the whole table.

  Put it right: Is that it removes rows, and the table definition remains.

• Believing DELETE changes a value in a row.

  Put it right: Is that UPDATE alters stored values, whereas DELETE removes whole rows.

• Assuming a statement without WHERE deletes nothing.

  Put it right: Is that it deletes every row in the table.

• Placing the condition before FROM.

  Put it right: Is that the table name follows FROM and the condition follows WHERE.

Exam tips

• Underline the table name and the condition in the statement before reading the options.
• Ask what happens to rows that do not meet the condition: they stay unchanged.
• Check whether the option keeps the table in existence, since deletion of rows is not deletion of the table.