information-schema-sequences.md

title	summary
SEQUENCES	了解 INFORMATION_SCHEMA 表 `SEQUENCES`。

SEQUENCES

SEQUENCES 表提供了有关序列的信息。TiDB 中序列的功能是参照 MariaDB 中的类似功能来实现的。

USE INFORMATION_SCHEMA;
DESC SEQUENCES;

输出结果如下：

+-----------------+--------------+------+------+---------+-------+
| Field           | Type         | Null | Key  | Default | Extra |
+-----------------+--------------+------+------+---------+-------+
| TABLE_CATALOG   | varchar(512) | NO   |      | NULL    |       |
| SEQUENCE_SCHEMA | varchar(64)  | NO   |      | NULL    |       |
| SEQUENCE_NAME   | varchar(64)  | NO   |      | NULL    |       |
| CACHE           | tinyint(0)   | NO   |      | NULL    |       |
| CACHE_VALUE     | bigint(21)   | YES  |      | NULL    |       |
| CYCLE           | tinyint(0)   | NO   |      | NULL    |       |
| INCREMENT       | bigint(21)   | NO   |      | NULL    |       |
| MAX_VALUE       | bigint(21)   | YES  |      | NULL    |       |
| MIN_VALUE       | bigint(21)   | YES  |      | NULL    |       |
| START           | bigint(21)   | YES  |      | NULL    |       |
| COMMENT         | varchar(64)  | YES  |      | NULL    |       |
+-----------------+--------------+------+------+---------+-------+
11 rows in set (0.00 sec)

创建一个名为 test.seq 的序列，并查询这个序列的下一个值：

CREATE SEQUENCE test.seq;
SELECT nextval(test.seq);

输出结果如下：

+-------------------+
| nextval(test.seq) |
+-------------------+
|                 1 |
+-------------------+
1 row in set (0.01 sec)

查询数据库中的所有序列：

SELECT * FROM SEQUENCES\G

输出结果如下：

*************************** 1. row ***************************
  TABLE_CATALOG: def
SEQUENCE_SCHEMA: test
  SEQUENCE_NAME: seq
          CACHE: 1
    CACHE_VALUE: 1000
          CYCLE: 0
      INCREMENT: 1
      MAX_VALUE: 9223372036854775806
      MIN_VALUE: 1
          START: 1
        COMMENT:
1 row in set (0.00 sec)