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From:Jesper Wisborg Krogh Date:February 25 2010 1:15pm
Subject:Re: Remove - Foreign key constraint in innodb
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An example how to delete a foreign key from an InnoDB table:

test> CREATE TABLE table_1 (id int unsigned NOT NULL auto_increment  
PRIMARY KEY) ENGINE=InnoDB;
Query OK, 0 rows affected (0.56 sec)

test> CREATE TABLE table_2 (table1_id int unsigned NOT NULL, FOREIGN  
KEY (table1_id) REFERENCES table_1 (id)) ENGINE=InnoDB;
Query OK, 0 rows affected (0.11 sec)

test> SHOW CREATE TABLE table_2\G
*************************** 1. row ***************************
        Table: table_2
Create Table: CREATE TABLE `table_2` (
   `table1_id` int(10) unsigned NOT NULL,
   KEY `table1_id` (`table1_id`),
   CONSTRAINT `table_2_ibfk_1` FOREIGN KEY (`table1_id`) REFERENCES  
`table_1` (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1
1 row in set (0.47 sec)

test> ALTER TABLE table_2 DROP FOREIGN KEY table_2_ibfk_1;
Query OK, 0 rows affected (0.11 sec)
Records: 0  Duplicates: 0  Warnings: 0

test> SHOW CREATE TABLE table_2\G
*************************** 1. row ***************************
        Table: table_2
Create Table: CREATE TABLE `table_2` (
   `table1_id` int(10) unsigned NOT NULL,
   KEY `table1_id` (`table1_id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1
1 row in set (0.00 sec)

On 25/02/2010, at 11:33 PM, Jim Lyons wrote:

> Yes - you can drop a foreign key constraint, use the 'alter  
> table ... drop
> foreign key ...' command.  If you get an error message, post the error
> message.
>
> On Thu, Feb 25, 2010 at 6:03 AM, Vikram A <vikkiatbipl@stripped>  
> wrote:
>
>> Hi,
>>
>> I tried to remove foreign key constraint in innodb table.
>>
>> I tried with different ways; but i am unable to drop the constraints.
>>
>>
>> http://lists.mysql.com/mysql/113053
>> It says that, droping the foreign key constraint it is not  
>> possible in
>> innodb engine.
>>
>> Is it so? or any other possibilities? I am using mysql 5.1.32
>>
>> Please, Can any one you help me?
>>
>> Thank you
>>
>> VIKRAM A
>>
>>
>>
>>      The INTERNET now has a personality. YOURS! See your Yahoo!  
>> Homepage.
>> http://in.yahoo.com/
>
>
>
>
> -- 
> Jim Lyons
> Web developer / Database administrator
> http://www.weblyons.com

Thread
Remove - Foreign key constraint in innodbVikram A25 Feb
  • Re: Remove - Foreign key constraint in innodbJim Lyons25 Feb
    • Re: Remove - Foreign key constraint in innodbJesper Wisborg Krogh25 Feb