MySQL 如何获取表的主键

要获取表的主键，可以使用show命令。语法如下 –

SHOW INDEX FROM yourDatebaseName.yourTableName WHERE Key_name = 'PRIMARY';

假设我们有一个具有两个主键的表，一个是“Id”，另一个是“RollNum”。表的查询如下 –

mysql> create table TwoOrMorePrimary
   −> (
   −> Id int,
   −> Name varchar(200), 
   −> RollNum int
   −> ,
   −> Primary key(Id,Age)
   −> );
Query OK, 0 rows affected (0.85 sec)

将以上语法应用于获取表的主键。查询如下 –

mysql> SHOW INDEX FROM business.TwoOrMorePrimary
−> WHERE Key_name = 'PRIMARY';

以下是输出 –

+------------------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+---------+------------+
| Table            | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment | Visible | Expression |
+------------------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+---------+------------+
| twoormoreprimary |          0 | PRIMARY  | 1            | Id          | A         | 0           | NULL     | NULL   |      | BTREE      |         |               | YES     | NULL       |
| twoormoreprimary |          0 | PRIMARY  | 2            | RollNum     | A         | 0           | NULL     | NULL   |      | BTREE      |         |               | YES      | NULL      |
+------------------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+---------+------------+
2 rows in set (0.12 sec)

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