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Two columns as primary key with auto-increment in MySQL?
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)
Updated on: 30-Jul-2019
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