LIMIT
Description
Use the LIMIT clause to restrict the number of returned rows. When you use a single
integer n with LIMIT, the first n rows will be returned. Use the ORDER BY
clause to control which rows come first. You can also select a number of rows after an offset
using either of the following:
LIMIT offset, row_count LIMIT row_count OFFSET offset
When you provide an offset m with a limit n, the first m rows will be ignored, and the following n rows will be returned.
Executing an UPDATE with the LIMIT clause is not safe for replication. LIMIT 0 is an exception to this rule (see MDEV-6170).
There is a LIMIT ROWS EXAMINED optimization which provides the means to terminate the execution of SELECT statements which examine too many rows, and thus use too many resources. See LIMIT ROWS EXAMINED.
Multi-Table Updates
Until MariaDB 10.3.1, it was not possible to use LIMIT (or ORDER BY) in a multi-table UPDATE statement. This restriction was lifted in MariaDB 10.3.2.
GROUP_CONCAT
Starting from MariaDB 10.3.3, it is possible to use LIMIT with GROUP_CONCAT().
Examples
CREATE TABLE members (name VARCHAR(20)); INSERT INTO members VALUES('Jagdish'),('Kenny'),('Rokurou'),('Immaculada'); SELECT * FROM members; +------------+ | name | +------------+ | Jagdish | | Kenny | | Rokurou | | Immaculada | +------------+
Select the first two names (no ordering specified):
SELECT * FROM members LIMIT 2; +---------+ | name | +---------+ | Jagdish | | Kenny | +---------+
All the names in alphabetical order:
SELECT * FROM members ORDER BY name; +------------+ | name | +------------+ | Immaculada | | Jagdish | | Kenny | | Rokurou | +------------+
The first two names, ordered alphabetically:
SELECT * FROM members ORDER BY name LIMIT 2; +------------+ | name | +------------+ | Immaculada | | Jagdish | +------------+
The third name, ordered alphabetically (the first name would be offset zero, so the third is offset two):
SELECT * FROM members ORDER BY name LIMIT 2,1; +-------+ | name | +-------+ | Kenny | +-------+
From MariaDB 10.3.2, LIMIT can be used in a multi-table update:
CREATE TABLE warehouse (product_id INT, qty INT); INSERT INTO warehouse VALUES (1,100),(2,100),(3,100),(4,100); CREATE TABLE store (product_id INT, qty INT); INSERT INTO store VALUES (1,5),(2,5),(3,5),(4,5); UPDATE warehouse,store SET warehouse.qty = warehouse.qty-2, store.qty = store.qty+2 WHERE (warehouse.product_id = store.product_id AND store.product_id >= 1) ORDER BY store.product_id DESC LIMIT 2; SELECT * FROM warehouse; +------------+------+ | product_id | qty | +------------+------+ | 1 | 100 | | 2 | 100 | | 3 | 98 | | 4 | 98 | +------------+------+ SELECT * FROM store; +------------+------+ | product_id | qty | +------------+------+ | 1 | 5 | | 2 | 5 | | 3 | 7 | | 4 | 7 | +------------+------+
From MariaDB 10.3.3, LIMIT can be used with GROUP_CONCAT, so, for example, given the following table:
CREATE TABLE d (dd DATE, cc INT); INSERT INTO d VALUES ('2017-01-01',1); INSERT INTO d VALUES ('2017-01-02',2); INSERT INTO d VALUES ('2017-01-04',3);
the following query:
SELECT SUBSTRING_INDEX(GROUP_CONCAT(CONCAT_WS(":",dd,cc) ORDER BY cc DESC),",",1) FROM d; +----------------------------------------------------------------------------+ | SUBSTRING_INDEX(GROUP_CONCAT(CONCAT_WS(":",dd,cc) ORDER BY cc DESC),",",1) | +----------------------------------------------------------------------------+ | 2017-01-04:3 | +----------------------------------------------------------------------------+
can be more simply rewritten as:
SELECT GROUP_CONCAT(CONCAT_WS(":",dd,cc) ORDER BY cc DESC LIMIT 1) FROM d; +-------------------------------------------------------------+ | GROUP_CONCAT(CONCAT_WS(":",dd,cc) ORDER BY cc DESC LIMIT 1) | +-------------------------------------------------------------+ | 2017-01-04:3 | +-------------------------------------------------------------+
