Two columns as primary key with auto-increment in MySQL?

MySQLMySQLi Database

Achieve this using MyISAM Engine. Here is an example of two columns as primary key with auto-increment.

Creating a table with two columns as primary key −

mysql> create table TwoPrimaryKeyTableDemo
   -> (
   -> Result ENUM('First','Second','Third','Fail') not null,
   -> StudentId int not null auto_increment,
   -> StudentName varchar(200) not null,
   -> Primary key(Result,StudentId)
   -> )
   -> ENGINE=MyISAM;
Query OK, 0 rows affected (0.20 sec)

Inserting records into table

mysql> insert into TwoPrimaryKeyTableDemo(StudentName,Result) values('John','Fail');
Query OK, 1 row affected (0.42 sec)
mysql> insert into TwoPrimaryKeyTableDemo(StudentName,Result)values('Carol','First');
Query OK, 1 row affected (0.09 sec)
mysql> insert into TwoPrimaryKeyTableDemo(StudentName,Result) values('Smith','Third');
Query OK, 1 row affected (0.05 sec)
mysql> insert into TwoPrimaryKeyTableDemo(StudentName,Result) values('Johnson','Second');
Query OK, 1 row affected (0.03 sec)
mysql> insert into TwoPrimaryKeyTableDemo(StudentName,Result) values('Johnson','Third');
Query OK, 1 row affected (0.06 sec)
mysql> insert into TwoPrimaryKeyTableDemo(StudentName,Result) values('Carol','Second');
Query OK, 1 row affected (0.18 sec)
mysql> insert into TwoPrimaryKeyTableDemo(StudentName,Result) values('Carol','Fail');
Query OK, 1 row affected (0.05 sec)

Now we can check the records with the help of select statement with order by clause. The query is as follows.

mysql> select *from TwoPrimaryKeyTableDemo order by StudentId,Result;

The following is the output −

+--------+-----------+-------------+
| Result | StudentId | StudentName |
+--------+-----------+-------------+
| First  | 1         | Carol       |
| Second | 1         | Johnson     |
| Third  | 1         | Smith       |
| Fail   | 1         | John        |
| Second | 2         | Carol       |
| Third  | 2         | Johnson     |
| Fail   | 2         | Carol       |
+--------+-----------+-------------+
7 rows in set (0.00 sec)
raja
Published on 21-Dec-2018 10:04:25
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