Create a sequence generator. This statement initializes a sequence object that produces a series of unique numeric values on demand.
The options for CREATE SEQUENCE can be given in any order, optionally followed by table_options.
table_options can be any of the normal table options in CREATE TABLE — the most used ones are ENGINE=... and COMMENT=.
NOMAXVALUE and NOMINVALUE are there to allow one to create SEQUENCEs using the Oracle syntax.
CREATE SEQUENCE creates a sequence that generates new values when called with NEXT VALUE FOR sequence_name. It's an alternative to if you want to have more control of how the numbers are generated. As the SEQUENCE caches values (up to CACHE), it can in some cases be much faster than . Another benefit is that you can access the last value generated by all used sequences, which solves one of the limitations with .
CREATE SEQUENCE requires the .
can be used to drop a sequence, and to change it.
INT type, that is, one of , , , , , . Can be signed or unsigned. Maximum value is based on the data type. The use of BIGINT UNSIGNED with this option extends the possible maximum value from 9223372036854775806 to 18446744073709551614. Default is BIGINT.
The AS option is not available.
Increment to use for values. May be negative. Setting an increment of 0 causes the sequence to use the value of the system variable at the time of creation, which is always a positive number. (see ). Default 1.
Minimum value for the sequence. From , the parser permits much smaller numbers, such as -9999999999999999999999999999, but converts to the minimum permitted for the INT type, with a note. Default 1 if INCREMENT > 0 , and -9223372036854775807 (or based on int type) if INCREMENT < 0.
Maximum value for sequence. From , the parser permits much larger numbers, such as 9999999999999999999999999999 used in Oracle examples, but converts to the maximum permitted for the INT type, with a note. Default 9223372036854775806 (or based on int type) if INCREMENT > 0 , and -1 if INCREMENT < 0.
First value the sequence will generate. Default MINVALUE if INCREMENT > 0, and MAX_VALUE if INCREMENT< 0.
Number of values that should be cached. 0 if no CACHE. The underlying table will be updated first time a new sequence number is generated and each time the cache runs out. Default 1000. , shutting down the server, etc. will discard the cached values, and the next sequence number generated will be according to what's stored in the Sequence object. In effect, this will discard the cached values.
Note that setting the cache to 1 from 1000 can make inserts to tables using sequences for default values 2x slower and increase the binary log sizes up to 7x.
If CYCLE is used, then the sequence should start again from MINVALUE after it has run out of values. Default value is NOCYCLE.
To be able to create a legal sequence, the following must hold:
MAXVALUE >= start
MAXVALUE > MINVALUE
START >= MINVALUE
Note that sequences can't generate the maximum/minimum 64 bit number because of the constraint ofMINVALUE and MAXVALUE.
MariaDB supports and CREATE SEQUENCE is atomic.
MariaDB does not support and CREATE SEQUENCE is atomic.
The following statement fails, as the increment conflicts with the defaults:
The sequence can be created by specifying workable minimum and maximum values:
From :
Parser accepting larger or smaller values:
Flushing the cache:
You can use sequences instead of AUTO_INCREMENT to generate values for a table:
This page is licensed: CC BY-SA / Gnu FDL
CREATE [OR REPLACE] [TEMPORARY] SEQUENCE [IF NOT EXISTS] sequence_name
[AS { TINYINT | SMALLINT | |MEDIUMINT | INT | INTEGER | BIGINT } [SIGNED | UNSIGNED]]
[ INCREMENT [ BY | = ] number ]
[ MINVALUE [=] number | NO MINVALUE | NOMINVALUE ]
[ MAXVALUE [=] number | NO MAXVALUE | NOMAXVALUE ]
[ START [ WITH | = ] number ]
[ CACHE [=] number | NOCACHE ] [ CYCLE | NOCYCLE]
[table_options](../sql-statements/data-definition/create/create-table.md#table-options)MAXVALUE <= 9223372036854775806 (LONGLONG_MAX-1). From , the parser accepts values beyond this, and converts based on the int type.
MINVALUE >= -9223372036854775807 (LONGLONG_MIN+1). From , the parser accepts values beyond this, and converts based on the int type.
SETVAL(). Set next value for the sequence.
CREATE SEQUENCE s START WITH 100 INCREMENT BY 10;
CREATE SEQUENCE s2 START WITH -100 INCREMENT BY -10;CREATE SEQUENCE s3 START WITH -100 INCREMENT BY 10;
ERROR 4082 (HY000): Sequence 'test.s3' values are conflictingCREATE SEQUENCE s3 START WITH -100 INCREMENT BY 10 MINVALUE=-100 MAXVALUE=1000;CREATE SEQUENCE s3 AS BIGINT UNSIGNED START WITH 10;CREATE OR REPLACE SEQUENCE s AS TINYINT SIGNED
MINVALUE=-999999999999999999999999999999999
MAXVALUE=999999999999999999999999999999999
START WITH 100 INCREMENT BY 10;
Query OK, 0 rows affected, 2 warnings (0.037 sec)
SHOW WARNINGS;
+-------+------+-----------------------------------------------+
| Level | Code | Message |
+-------+------+-----------------------------------------------+
| Note | 1292 | Truncated incorrect INTEGER value: 'MINVALUE' |
| Note | 1292 | Truncated incorrect INTEGER value: 'MAXVALUE' |
+-------+------+-----------------------------------------------+
SELECT * FROM INFORMATION_SCHEMA.SEQUENCES\G
*************************** 1. row ***************************
SEQUENCE_CATALOG: def
SEQUENCE_SCHEMA: test
SEQUENCE_NAME: s
DATA_TYPE: tinyint
NUMERIC_PRECISION: 8
NUMERIC_PRECISION_RADIX: 2
NUMERIC_SCALE: 0
START_VALUE: 100
MINIMUM_VALUE: -127
MAXIMUM_VALUE: 126
INCREMENT: 10
CYCLE_OPTION: 0CREATE OR REPLACE SEQUENCE s START WITH 1 INCREMENT BY 1 MAXVALUE=10 CACHE=5;
SELECT NEXTVAL(s);
+------------+
| NEXTVAL(s) |
+------------+
| 1 |
+------------+
SELECT NEXTVAL(s);
+------------+
| NEXTVAL(s) |
+------------+
| 2 |
+------------+
FLUSH TABLES s;
SELECT NEXTVAL(s);
+------------+
| NEXTVAL(s) |
+------------+
| 6 |
+------------+
FLUSH TABLES s;
SELECT NEXTVAL(s);
ERROR 4084 (HY000): Sequence 'test.s' has run outCREATE SEQUENCE s1;
CREATE TABLE t1 (a INT PRIMARY KEY DEFAULT nextval(s1), b INT);
INSERT INTO t1 (b) VALUES(1);
SELINT * FROM t1;
+---+------+
| a | b |
+---+------+
| 1 | 1 |
+---+------+