EXCEPT
MariaDB starting with 10.3.0
EXCEPT was introduced in MariaDB 10.3.0.
The result of EXCEPT
is all records of the left SELECT
result set except records which are in right SELECT
result set, i.e. it is subtraction of two result sets. From MariaDB 10.6.1, MINUS
is a synonym.
Syntax
SELECT ... (INTERSECT [ALL | DISTINCT] | EXCEPT [ALL | DISTINCT] | UNION [ALL | DISTINCT]) SELECT ... [(INTERSECT [ALL | DISTINCT] | EXCEPT [ALL | DISTINCT] | UNION [ALL | DISTINCT]) SELECT ...] [ORDER BY [column [, column ...]]] [LIMIT {[offset,] row_count | row_count OFFSET offset} | OFFSET start { ROW | ROWS } | FETCH { FIRST | NEXT } [ count ] { ROW | ROWS } { ONLY | WITH TIES } ]
Contents
Please note:
- Brackets for explicit operation precedence are not supported; use a subquery in the
FROM
clause as a workaround).
Description
MariaDB has supported EXCEPT
and INTERSECT in addition to UNION since MariaDB 10.3.
The queries before and after EXCEPT
must be SELECT or VALUES statements.
All behavior for naming columns, ORDER BY
and LIMIT
is the same as for UNION
. Note that the alternative SELECT ... OFFSET ... FETCH syntax is only supported. This allows us to use the WITH TIES
clause.
EXCEPT
implicitly supposes a DISTINCT
operation.
The result of EXCEPT
is all records of the left SELECT
result except records which are in right SELECT
result set, i.e. it is subtraction of two result sets.
EXCEPT
and UNION
have the same operation precedence and INTERSECT
has a higher precedence, unless running in Oracle mode, in which case all three have the same precedence.
MariaDB starting with 10.4.0
Parentheses
From MariaDB 10.4.0, parentheses can be used to specify precedence. Before this, a syntax error would be returned.
MariaDB starting with 10.5.0
ALL/DISTINCT
EXCEPT ALL
and EXCEPT DISTINCT
were introduced in MariaDB 10.5.0. The ALL
operator leaves duplicates intact, while the DISTINCT
operator removes duplicates. DISTINCT
is the default behavior if neither operator is supplied, and the only behavior prior to MariaDB 10.5.
Examples
Show customers which are not employees:
(SELECT e_name AS name, email FROM customers) EXCEPT (SELECT c_name AS name, email FROM employees);
Difference between UNION, EXCEPT and INTERSECT. INTERSECT ALL
and EXCEPT ALL
are available from MariaDB 10.5.0.
CREATE TABLE seqs (i INT); INSERT INTO seqs VALUES (1),(2),(2),(3),(3),(4),(5),(6); SELECT i FROM seqs WHERE i <= 3 UNION SELECT i FROM seqs WHERE i>=3; +------+ | i | +------+ | 1 | | 2 | | 3 | | 4 | | 5 | | 6 | +------+ SELECT i FROM seqs WHERE i <= 3 UNION ALL SELECT i FROM seqs WHERE i>=3; +------+ | i | +------+ | 1 | | 2 | | 2 | | 3 | | 3 | | 3 | | 3 | | 4 | | 5 | | 6 | +------+ SELECT i FROM seqs WHERE i <= 3 EXCEPT SELECT i FROM seqs WHERE i>=3; +------+ | i | +------+ | 1 | | 2 | +------+ SELECT i FROM seqs WHERE i <= 3 EXCEPT ALL SELECT i FROM seqs WHERE i>=3; +------+ | i | +------+ | 1 | | 2 | | 2 | +------+ SELECT i FROM seqs WHERE i <= 3 INTERSECT SELECT i FROM seqs WHERE i>=3; +------+ | i | +------+ | 3 | +------+ SELECT i FROM seqs WHERE i <= 3 INTERSECT ALL SELECT i FROM seqs WHERE i>=3; +------+ | i | +------+ | 3 | | 3 | +------+
Parentheses for specifying precedence, from MariaDB 10.4.0
CREATE OR REPLACE TABLE t1 (a INT); CREATE OR REPLACE TABLE t2 (b INT); CREATE OR REPLACE TABLE t3 (c INT); INSERT INTO t1 VALUES (1),(2),(3),(4); INSERT INTO t2 VALUES (5),(6); INSERT INTO t3 VALUES (1),(6); ((SELECT a FROM t1) UNION (SELECT b FROM t2)) EXCEPT (SELECT c FROM t3); +------+ | a | +------+ | 2 | | 3 | | 4 | | 5 | +------+ (SELECT a FROM t1) UNION ((SELECT b FROM t2) EXCEPT (SELECT c FROM t3)); +------+ | a | +------+ | 1 | | 2 | | 3 | | 4 | | 5 | +------+
Here is an example that makes use of the SEQUENCE storage engine and the VALUES statement, to generate a numeric sequence and remove some arbitrary numbers from it:
(SELECT seq FROM seq_1_to_10) EXCEPT VALUES (2), (3), (4); +-----+ | seq | +-----+ | 1 | | 5 | | 6 | | 7 | | 8 | | 9 | | 10 | +-----+
See Also
- UNION
- INTERSECT
- Get Set for Set Theory: UNION, INTERSECT and EXCEPT in SQL (video tutorial)