SHOW CREATE TABLE
当表为拆分表或者广播表时,显示自增列Sequence的类型。
查看已创建的表语法如下:
SHOW CREATE TABLE <name>
说明
SHOW CREATE TABLE
仅显示相关Sequence的类型,并不显示Sequence详细信息,如需查看,请使用SHOW SEQUENCES
命令。- 关联了单元化Group Sequence的表并不显示单元数量和单元索引,因此不能将
SHOW CREATE TABLE
显示的DDL直接用于创建具备同样单元化Group Sequence能力的表。 - 如果需要创建具备同样单元化能力的表,必须使用
SHOW SEQUENCES
查看单元数量和单元索引,然后参照CREATE TABLE
的语法修改通过SHOW CREATE TABLE
获取的建表DDL。
示例
示例一:建表时指定AUTO_INCREMENT
,但没有指定Sequence类型关键字,则默认使用Group Sequence。
请在命令行输入如下代码:
mysql> SHOW CREATE TABLE tab1;
返回结果如下:
+-------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table | Create Table |+-------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| tab1 | CREATE TABLE `tab1` (
`col1` bigint(20) NOT NULL AUTO_INCREMENT BY GROUP,
`col2` varchar(16) DEFAULT NULL,
PRIMARY KEY (`col1`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 dbpartition by hash(`col1`) |
+-------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.02 sec)
示例二:建表时为AUTO_INCREMENT
指定了单元数量和单元索引,使用单元化 Group Sequence,但SHOW CREATE TABLE
时并不显示单元数量和单元索引,不能将此DDL用于创建具备同样单元化 Group Sequence能力的表。
请在命令行输入如下代码:
mysql> SHOW CREATE TABLE tab2;
返回结果如下:
+-------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table | Create Table |
+-------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| tab2 | CREATE TABLE `tab2` (
`col1` bigint(20) NOT NULL AUTO_INCREMENT BY GROUP,
`col2` varchar(16) DEFAULT NULL,
PRIMARY KEY (`col1`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 dbpartition by hash(`col1`) |
+-------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.01 sec)
示例三:建表时为AUTO_INCREMENT
指定了BY TIME
,即Time-based Sequence类型。
请在命令行输入如下代码:
mysql> SHOW CREATE TABLE tab3;
返回结果如下:
+-------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table | Create Table |
+-------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| tab3 | CREATE TABLE `tab3` (
`col1` bigint(20) NOT NULL AUTO_INCREMENT BY TIME,
`col2` varchar(16) DEFAULT NULL,
PRIMARY KEY (`col1`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 dbpartition by hash(`col1`) |
+-------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.01 sec)
示例四:建表时为AUTO_INCREMENT
指定了BY SIMPLE
,即Simple Sequence类型。
请在命令行输入如下代码:
mysql> SHOW CREATE TABLE tab4;
返回结果如下:
+-------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table | Create Table |
+-------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| tab3 | CREATE TABLE `tab4` (
`col1` bigint(20) NOT NULL AUTO_INCREMENT BY TIME,
`col2` varchar(16) DEFAULT NULL,
PRIMARY KEY (`col1`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 dbpartition by hash(`col1`) |
+-------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.01 sec)
SHOW SEQUENCES
建表后相关的Sequence名称和详细信息,可通过SHOW SEQUENCES
查看。
请在命令行输入如下代码:
mysql> SHOW SEQUENCES;
返回结果如下:
+---------------+--------+------------+------------+------------+--------------+------------+---------------------+-------+--------+
| NAME | VALUE | UNIT_COUNT | UNIT_INDEX | INNER_STEP | INCREMENT_BY | START_WITH | MAX_VALUE | CYCLE | TYPE |
+---------------+--------+------------+------------+------------+--------------+------------+---------------------+-------+--------+
| seq1 | 100000 | 1 | 0 | 100000 | N/A | N/A | N/A | N/A | GROUP |
| seq2 | 400000 | 3 | 1 | 100000 | N/A | N/A | N/A | N/A | GROUP |
| seq3 | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | TIME |
| seq4 | 1006 | N/A | N/A | N/A | 2 | 1000 | 99999999999 | N | SIMPLE |
| AUTO_SEQ_tab1 | 100000 | 1 | 0 | 100000 | N/A | N/A | N/A | N/A | GROUP |
| AUTO_SEQ_tab2 | 400000 | 3 | 1 | 100000 | N/A | N/A | N/A | N/A | GROUP |
| AUTO_SEQ_tab3 | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | TIME |
| AUTO_SEQ_tab4 | 2 | N/A | N/A | N/A | 1 | 1 | 9223372036854775807 | N | SIMPLE |
+---------------+--------+------------+------------+------------+--------------+------------+---------------------+-------+--------+
8 rows in set (0.01 sec)