我们可以在 MySQL 中使用 PRIMARY KEY( colomn1, column2) 来创建对吗?
是的,你可以使用下面的语法。以下为语法 -
PRIMARY KEY(yourColumnName1,yourColumnName2);
我们首先创建一个表 -
mysql> create table DemoTable -> ( -> StudentFirstName varchar(100), -> StudentLastName varchar(100), -> StudentAge int, -> StudentCountryName varchar(100), -> PRIMARY KEY(StudentFirstName,StudentLastName) -> ); Query OK, 0 rows affected (0.74 sec)
让我们检查表的描述 -
mysql> desc DemoTable;
输出
这会产生以下输出 -
+--------------------+--------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +--------------------+--------------+------+-----+---------+-------+ | StudentFirstName | varchar(100) | NO | PRI | NULL | | | StudentLastName | varchar(100) | NO | PRI | NULL | | | StudentAge | int(11) | YES | | NULL | | | StudentCountryName | varchar(100) | YES | | NULL | | +--------------------+--------------+------+-----+---------+-------+ 4 rows in set (0.00 sec)
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