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ALTER table by adding AUTOINCREMENT in MySQL?
To add AUTOINCREMENT in MySQL, you can use the ALTER command.
ALTER TABLE yourTableName change yourColumName yourColumnName dataType AUTO_INCREMENT PRIMARY KEY;
To understand the above concept, create a table with a column. Let us create a table −
mysql> create table AlterTableToAddAutoIncrement -> ( -> StudentId int -> ); Query OK, 0 rows affected (0.57 sec)
Implement the above syntax to change “StudentId” with AUTOINCREMENT. The query is as follows −
mysql> alter table AlterTableToAddAutoIncrement change StudentId StudentId int AUTO_INCREMENT Primary key; Query OK, 0 rows affected (1.93 sec) Records: 0 Duplicates: 0 Warnings: 0
We have added AUTO_INCREMENT to column name ‘StudentId’. Now you can verify whether autoincrement is working or not by inserting records without giving any value.
The query is as follows −
mysql> insert into AlterTableToAddAutoIncrement values(); Query OK, 1 row affected (0.16 sec) mysql> insert into AlterTableToAddAutoIncrement values(); Query OK, 1 row affected (0.16 sec) mysql> insert into AlterTableToAddAutoIncrement values(); Query OK, 1 row affected (0.33 sec)
Now you can display all records which will be displayed in sequence of 1, 2, 3, 4, etc. The query is as follows −
mysql> select *from AlterTableToAddAutoIncrement;
The following is the output −
+-----------+ | StudentId | +-----------+ | 1 | | 2 | | 3 | +-----------+ 3 rows in set (0.00 sec)
Updated on: 30-Jul-2019
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