DELETE

The DELETE statement removes rows from the table identified by the table-name. If the WHERE clause is not present, all records in the table are deleted. If a WHERE clause is supplied, then only those rows for which the WHERE clause results in true are deleted. Rows for which the expression is false or NULL are retained.

Examples

Remove the rows matching the condition i = 2 from the database:

Query

DELETE FROM tbl WHERE i = 2;

Delete all rows in the table tbl:

Query

DELETE FROM tbl;

USING Clause

The USING clause allows deleting based on the content of other tables or subqueries.

RETURNING Clause

The RETURNING clause allows returning the deleted values. It uses the same syntax as the SELECT clause except the DISTINCT modifier is not supported.

Query

CREATE TABLE employees (name VARCHAR, age INTEGER);
INSERT INTO employees VALUES ('Kat', 32);
DELETE FROM employees RETURNING name, 2025 - age AS approx_birthyear;

Result

 name | approx_birthyear------+------------------ Kat  |             1993

Syntax

The TRUNCATE Statement

The TRUNCATE statement removes all rows from a table, acting as an alias for DELETE FROM without a WHERE clause:

Query

TRUNCATE tbl;

Limitations on Reclaiming Memory and Disk Space

Running DELETE does not mean space is reclaimed. In general, rows are only marked as deleted. SereneDB reclaims space upon performing a CHECKPOINT. VACUUM currently does not reclaim space.