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MySQL: What is 'AUTO_INCREMENT=5' in a create table query?
The AUTO_INCREMENT=5 in a create table query tells that the first record will start from 5 i.e. not default 1. As we know if you do not set the value to AUTO_INCREMENT then MySQL starts from 1 by default.
The syntax is as follows:
CREATE TABLE yourTableName ( yourColumnName1 dataType NOT NULL AUTO_INCRMENT, . . . N, PRIMARY KEY(yourColumnName1 ) )AUTO_INCREMENT=5;
To understand the above syntax, let us create a table.
Case1 − The table starts auto increment from 1 because it is the default standard.
The query to create a table is as follows:
mysql> create table defaultAutoIncrementDemo -> ( -> Id int NOT NULL AUTO_INCREMENT, -> Name varchar(10), -> PRIMARY KEY(Id) -> ); Query OK, 0 rows affected (2.19 sec)
Now you can insert some records in the table using insert command. The query is as follows:
mysql> insert into defaultAutoIncrementDemo(Name) values('John');
Query OK, 1 row affected (0.23 sec)
mysql> insert into defaultAutoIncrementDemo(Name) values('James');
Query OK, 1 row affected (0.14 sec)
mysql> insert into defaultAutoIncrementDemo(Name) values('Robert');
Query OK, 1 row affected (0.14 sec)
mysql> insert into defaultAutoIncrementDemo(Name) values('Mike');
Query OK, 1 row affected (0.13 sec)Now you can display all records and check the row will start from 1. The query is as follows:
mysql> select *from defaultAutoIncrementDemo;
The following is the output:
+----+--------+ | Id | Name | +----+--------+ | 1 | John | | 2 | James | | 3 | Robert | | 4 | Mike | +----+--------+ 4 rows in set (0.00 sec)
Case2 − Here is the query to start the auto_increment from 5. The query to create a table is as follows:
mysql> create table AutoIncrementStartsFrom5 -> ( -> Id int NOT NULL AUTO_INCREMENT, -> Name varchar(10), -> PRIMARY KEY(Id) -> )AUTO_INCREMENT=5; Query OK, 0 rows affected (1.00 sec)
Now insert some records in the table using insert command. The query is as follows:
mysql> insert into AutoIncrementStartsFrom5(Name) values('Larry');
Query OK, 1 row affected (0.15 sec)
mysql> insert into AutoIncrementStartsFrom5(Name) values('David');
Query OK, 1 row affected (0.20 sec)
mysql> insert into AutoIncrementStartsFrom5(Name) values('Bob');
Query OK, 1 row affected (0.13 sec)
mysql> insert into AutoIncrementStartsFrom5(Name) values('Ricky');
Query OK, 1 row affected (0.14 sec)Display all records from the table using select statement. The query is as follows:
mysql> select *from AutoIncrementStartsFrom5;
The following is the output:
+----+-------+ | Id | Name | +----+-------+ | 5 | Larry | | 6 | David | | 7 | Bob | | 8 | Ricky | +----+-------+ 4 rows in set (0.00 sec)
Look at the sample output, the auto_increment starts from 5.
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