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Editorial Team
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Asked: 2026-05-27T18:06:31+00:00

In phpMyAdmin when i try to add foreign key some error occurs and does

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In phpMyAdmin when i try to add foreign key some error occurs and does not tell what is wrong. Just says “FK fails”.

Can any one tell what is the problem?

Error

SQL query:

ALTER TABLE `hotel` ADD FOREIGN KEY ( `type_id` ) REFERENCES `hotel`.`hotel_type` (
`id`
) ON DELETE CASCADE ON UPDATE CASCADE ;

MySQL said: Documentation
#1452 - Cannot add or update a child row: a foreign key constraint fails (`hotel`.`#sql-cfc_e`, CONSTRAINT `#sql-cfc_e_ibfk_2` FOREIGN KEY (`type_id`) REFERENCES `hotel_type` (`id`) ON DELETE CASCADE ON UPDATE CASCADE)
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1 Answer

  1. Editorial Team

    Be sure the columns of both tables are of the same data-type:

    hotel.hotel type_id int(11) unsigned # type_id column of hotel table

hotel.hotel_type id int(11) unsigned # id column of hotel_type table

    If they are not of the same type then you won’t be able to add your FK constraint.

    — Edit —

    Based on your response, the columns are the same data-types, so that means you have an invalid value in the hotels.type_id column (value doesn’t exist in the hotel_types table). Check the values in your hotels.type_id column and make sure they exist in your hotel_types.id column.

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