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。

  1. USE INFORMATION_SCHEMA;
  2. DESC SEQUENCES;

输出结果如下：

  1. +-----------------+--------------+------+------+---------+-------+
  2. | Field           | Type         | Null | Key  | Default | Extra |
  3. +-----------------+--------------+------+------+---------+-------+
  4. | TABLE_CATALOG   | varchar(512) | NO   |      | NULL    |       |
  5. | SEQUENCE_SCHEMA | varchar(64)  | NO   |      | NULL    |       |
  6. | SEQUENCE_NAME   | varchar(64)  | NO   |      | NULL    |       |
  7. | CACHE           | tinyint(0)   | NO   |      | NULL    |       |
  8. | CACHE_VALUE     | bigint(21)   | YES  |      | NULL    |       |
  9. | CYCLE           | tinyint(0)   | NO   |      | NULL    |       |
  10. | INCREMENT       | bigint(21)   | NO   |      | NULL    |       |
  11. | MAX_VALUE       | bigint(21)   | YES  |      | NULL    |       |
  12. | MIN_VALUE       | bigint(21)   | YES  |      | NULL    |       |
  13. | START           | bigint(21)   | YES  |      | NULL    |       |
  14. | COMMENT         | varchar(64)  | YES  |      | NULL    |       |
  15. +-----------------+--------------+------+------+---------+-------+
  16. 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：

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

输出结果如下：

  1. +-------------------+
  2. | nextval(test.seq) |
  3. +-------------------+
  4. |                 1 |
  5. +-------------------+
  6. 1 row in set (0.01 sec)

查询数据库中的所有序列：

  1. SELECT * FROM SEQUENCES\G

输出结果如下：

  1. *************************** 1. row ***************************
  2.   TABLE_CATALOG: def
  3. SEQUENCE_SCHEMA: test
  4.   SEQUENCE_NAME: seq
  5.           CACHE: 1
  6.     CACHE_VALUE: 1000
  7.           CYCLE: 0
  8.       INCREMENT: 1
  9.       MAX_VALUE: 9223372036854775806
  10.       MIN_VALUE: 1
  11.           START: 1
  12.         COMMENT:
  13. 1 row in set (0.00 sec)