|
Example In this example, we have created a table ‘Student123’ by defining column ‘RollNo’ with UNIQUE and NOT NULL constraints. Now, by describing the table we can see that ‘RollNo’ is the PRIMARY KEY column. mysql> Create table Student123(RollNo INT UNIQUE NOT NULL, Name varchar(20));
Query OK, 0 rows affected (0.25 sec)
mysql> DESCRIBE Student123;
+--------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+--------+-------------+------+-----+---------+-------+
| RollNo | int(11) | NO | PRI | NULL | |
| Name | varchar(20) | YES | | NULL | |
+--------+-------------+------+-----+---------+-------+
2 rows in set (0.04 sec) 登录后复制 |
