Question

I have tried adding a foreign key like this…

ALTER TABLE OrderLineItem
ADD CONSTRAINT
        FK_OrderLineItem_ShippingType_name FOREIGN KEY
(shippingType)
REFERENCES ShippingType(name);

Or like this in Mysql 5.5…

alter table OrderLineItem add foreign key 
FK_OrderLineItem_ShippingType (shippingType) references ShippingType(name);

Every time I see the following error.

[2011-11-18 15:07:04] [HY000][150] Create table
‘realtorprint_dev_dev/#sql-7d0_80’ with foreign key constraint failed.
There is no index in the referenced table where the referenced columns
appear as the first columns.

[2011-11-18 15:07:04] [HY000][1005] Can’t create table
‘realtorprint_dev_dev.#sql-7d0_80’ (errno: 150)

Both OrderLineItem.shippingType and ShippingType.name have a type of varchar(50) not null. ShippingType.name is the primaryKey of ShippingType.

Here is the result of show create table on ShippingType as well as OrderLineItem…

CREATE TABLE `shippingtype` (
  `name` varchar(50) CHARACTER SET latin1 NOT NULL DEFAULT '',
  `description` varchar(255) CHARACTER SET latin1 NOT NULL,
  PRIMARY KEY (`name`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

CREATE TABLE `orderlineitem` (
  `id` bigint(20) NOT NULL AUTO_INCREMENT,
  `description` varchar(255) CHARACTER SET latin1 NOT NULL,
  `lineNumber` int(11) NOT NULL,
  `quantity` int(11) NOT NULL,
  `quantityMultiplier` int(11) NOT NULL,
  `unitPrice` decimal(10,2) NOT NULL,
  `order_id` bigint(20) NOT NULL,
  `productDefinition_id` bigint(20) NOT NULL,
  `mlsId` varchar(255) CHARACTER SET latin1 DEFAULT NULL,
  `printProviderUnitCost` decimal(10,2) NOT NULL,
  `shippingType` varchar(50) NOT NULL,
  `address` varchar(255) DEFAULT NULL,
  `zipPostal` varchar(255) NOT NULL,
  `city` varchar(255) NOT NULL,
  `stateProvince` varchar(255) NOT NULL,
  `country` varchar(255) DEFAULT NULL,
  PRIMARY KEY (`id`),
  KEY `idx_OrderLineItem_productDefinition_id` (`productDefinition_id`),
  KEY `idx_OrderLineItem_order_id` (`order_id`),
  CONSTRAINT `FK_OrderLineItem_order_id` FOREIGN KEY (`order_id`) REFERENCES `userorder` (`id`),
  CONSTRAINT `FK_OrderLineItem_productDefinition_id` FOREIGN KEY (`productDefinition_id`) REFERENCES `productdefinition` (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=10029 DEFAULT CHARSET=utf8;

Answer 1

It is possible is that Mysql gives this bad error when the column types do not match exactly – check collation / size etc.