mysql #1215 - Cannot add foreign key constraint - but why? - mysql

Question

we have the following script:
CREATE TABLE `dataBodyChanges` (
`id` int( 10 ) unsigned NOT NULL AUTO_INCREMENT ,
`numberOfContainers` int( 11 ) NOT NULL ,
`quantityPerContainer` int( 11 ) NOT NULL ,
`grossWeight` double NOT NULL ,
`comment` varchar( 1000 ) NOT NULL ,
`file` int( 10 ) unsigned DEFAULT NULL ,
`user` int( 10 ) unsigned NOT NULL ,
`dataBodyId` int( 10 ) unsigned NOT NULL ,
`created_at` timestamp NULL DEFAULT NULL ,
`updated_at` timestamp NULL DEFAULT NULL ,
PRIMARY KEY ( `id` ) ,
KEY `databodychanges_databodyid_foreign` ( `dataBodyId` ) ,
CONSTRAINT `databodychanges_databodyid_foreign` FOREIGN KEY ( `dataBodyId` ) REFERENCES `dataBodies` ( `id` )
) ENGINE = InnoDB AUTO_INCREMENT =1113 DEFAULT CHARSET = utf8;
with mysql output:
1215 - Cannot add foreign key constraint
the other table is:
USE material;
CREATE TABLE `dataBodies` (
`id` int(10) unsigned NOT NULL AUTO_INCREMENT,
`partNumber` varchar(8) COLLATE utf8mb4_unicode_ci DEFAULT NULL,
`totalOrderQuantity` varchar(9) COLLATE utf8mb4_unicode_ci DEFAULT NULL,
`containerPart` varchar(8) COLLATE utf8mb4_unicode_ci DEFAULT NULL,
`numberOfContainers` varchar(9) COLLATE utf8mb4_unicode_ci DEFAULT NULL,
`quantityPerContainer` varchar(9) COLLATE utf8mb4_unicode_ci DEFAULT NULL,
`kanbanNumber` varchar(4) COLLATE utf8mb4_unicode_ci DEFAULT NULL,
`matHandlingCode` varchar(12) COLLATE utf8mb4_unicode_ci DEFAULT NULL,
`grossWeight` varchar(9) COLLATE utf8mb4_unicode_ci DEFAULT NULL,
`partRemarks` varchar(18) COLLATE utf8mb4_unicode_ci DEFAULT NULL,
`AI11Z` varchar(50) COLLATE utf8mb4_unicode_ci DEFAULT NULL,
`AI12Z` varchar(50) COLLATE utf8mb4_unicode_ci DEFAULT NULL,
`AI13Z` varchar(50) COLLATE utf8mb4_unicode_ci DEFAULT NULL,
`AI14Z` varchar(50) COLLATE utf8mb4_unicode_ci DEFAULT NULL,
`AI15Z` varchar(50) COLLATE utf8mb4_unicode_ci DEFAULT NULL,
`AI16Z` varchar(50) COLLATE utf8mb4_unicode_ci DEFAULT NULL,
`AI17Z` varchar(50) COLLATE utf8mb4_unicode_ci DEFAULT NULL,
`filler` varchar(163) COLLATE utf8mb4_unicode_ci DEFAULT NULL,
`dataHeaderId` int(10) unsigned DEFAULT NULL,
`created_at` timestamp NULL DEFAULT NULL,
`updated_at` timestamp NULL DEFAULT NULL,
PRIMARY KEY (`id`),
KEY `databodies_dataheaderid_foreign` (`dataHeaderId`),
CONSTRAINT `databodies_dataheaderid_foreign` FOREIGN KEY (`dataHeaderId`) REFERENCES `dataHeaders` (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=1113 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;
We do not know why....
can anybody please help who is master in this?
Thank you in advance!

Answer 1

When you are creating tables, it will check if dependent table is already created, if not it will throw that error.
For which you first need to set,
set foreign_key_checks = false; // above all
Above line will temporarily disable foreign key checks if any.
Then run above query. It will work. then after executing your queries, enable it by,
set foreign_key_checks = true;