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mysql errorno 121

mysql errorno 121  using -'mysql,foreign-keys,mysql-error-1005'

I'm getting this error in MySQL create. I'm doing:

CREATE TABLE `blogReply` (

    `Id`      INT(24)      NOT NULL AUTO_INCREMENT COMMENT 'Primary Key of This Table',
    `blogId`  INT(24)      NOT NULL COMMENT 'Blog where this reply was posted',
    `userId`  INT(24)      NULL COMMENT 'User the blog was posted by',
    `name`    VARCHAR(100) NULL DEFAULT 'Unknown' COMMENT 'The Name of the user that the reply was posted by',
    `email`   VARCHAR(100) NULL DEFAULT 'Unknown' COMMENT 'The Email of the user that the reply was posted by',
    `http`    VARCHAR(300) NULL DEFAULT 'Unknown' COMMENT 'The Webaddress of the user that the reply was posted by',
    `message` TEXT         NOT NULL COMMENT 'text of the blog',
    `votes`   INT(10)      DEFAULT 0 COMMENT 'Rating of the Blog',
    `ratedBy` TEXT         COMMENT 'People who have already Voted on this blog',
    `dateReg` BIGINT       NOT NULL COMMENT 'Date the User was Registered',

    PRIMARY KEY (`Id`),

    CONSTRAINT `FK_userId` FOREIGN KEY(`userId`)
        REFERENCES `user` (`Id`)

    CONSTRAINT `FK_blogId` FOREIGN KEY(`blogId`)
        REFERENCES `blog` (`Id`)

) ENGINE = InnoDB;

Any Ideas? The Error States: Can't create table './xxxxxxxx/blogReply.frm' (errno: 121)

asked Sep 14, 2015 by ManieEddingt
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3 Answers

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Check that all your constraints are really spelled out correctly, also check that there's not any other tables that uses the constraint names FK_userId or FK_blogId

answered Sep 14, 2015 by KraCosgrove
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please check that your foreign key which you are creating is same in all aspects such as datatype with the referred table column . Each foreign key name should be unique for those tables in which it is created , it should not be used in anyother tables. for the above problem the Foreign key name "FK_userId" should not be used in any other table .

answered Sep 14, 2015 by GayleMcclint
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Error 121 is a foreign key constraint issue. The first thing to check is that your foreign key definitions are ok (all the tables and field names are correct, etc.).

You can try disabling foreign key checks before creating the table as well, like this:


That has the downside of throwing errors later when you re-enable your key checks (set it to 1), however, if this is the case, then it means you have some invalid records somewhere that are interfering with the creation of the foreign key.

However, this issue can also occur if you've been manually moving database files around, such as physically renaming the data/your_database_name directory. InnoDB can't correlate physical changes like that to the tablespace, so it mucks with the internals.

If this is what you did, the solution that works best is to move your old database back to where it was, take a dump or export of it, and do a DROP DATABASE on it before re-importing.

answered Sep 14, 2015 by CarHedley