I had to make sure that the tables reverse engineered from MySQL were defined as InnoDB. On further research there were several things that I needed to do for this to work. I think I'm creating the foreign keys correctly, so is there a reason its not importing them? If I look at the table data, and the foreign keys tab, theres nothing there? Here are the 2 demo tables that I am trying to get to work: CREATE TABLE users (ĬONSTRAINT fk_OrgID_Users FOREIGN KEY (OrgID) REFERENCES Organisations(OrgID)īut in MySQL Workbench, there are no relationships or foreign keys being created. While I am trying to get this to work I am using a snippet of a couple of tables, so its nothing complex. Which means I cant get it to draw the relationships. The length of string types need not be the same.I am reverse engineering a database in MySQL Workbench but it doesn't seem to be importing or recognising the foreign keys. The size and sign of integer types must be A foreign key constraint is a rule that enforces the relationship between two tables. In this case, we are adding a foreign key constraint to the Movie table. The cause of our error was due to violation of following rule:Ĭorresponding columns in the foreign key and the referenced key must ALTER TABLE Movie ADD FOREIGN KEY (Year) REFERENCES YearStats (Year) ON DELETE NO ACTION The ALTER TABLE statement is used to modify the structure of an existing table. So if the index in referenced table is exist and it is consists from several columns, and desired column is not first, the error shall be occurred. Where the referenced columns are listed as the first columns in the However, in the referenced table, there must be an index InnoDB permits a foreign key to reference any index column or group ofĬolumns. Referencing table, there must be an index where the foreign keyĬolumns are listed as the first columns in the same order. MySQL requires indexes on foreign keys and referenced keys so thatįoreign key checks can be fast and not require a table scan. Does anyone have any suggestions? And what is meant by first columns? So I guess the problem must be thatĬannot find an index in the referenced table where the referenced columns appear as the first columns.īut I'm not quite sure what this means, or how to check/fix it. (I also tried setting the experiment column to not null, but this didn't fix it). mysql> ALTER TABLE products ADD COLUMN supplierID INT UNSIGNED NOT NULL Output: Query OK. To me, the column types seem to match, since they are both varchar(45). 4.12.3 FOREIGN KEY Now, we shall add a foreign key. In the table and the referenced table do not match for constraint. Referenced columns appear as the first columns, or column types To get some more information, I did: SHOW ENGINE INNODB STATUS\Gįrom which I got: FOREIGN KEY (experiment) REFERENCES exp (EID)Ĭannot find an index in the referenced table where the Insert_date timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,ĬONSTRAINT FOREIGN KEY (inserted_by) REFERENCES user (iduser),ĬONSTRAINT FOREIGN KEY (target) REFERENCES protein (PID),ĬONSTRAINT FOREIGN KEY (sample_type) REFERENCES sample_type (ID),ĬONSTRAINT FOREIGN KEY (assay) REFERENCES assays (AID),ĬONSTRAINT FOREIGN KEY (experiment) REFERENCES exp (EID)ĮRROR 1215 (HY000): Cannot add foreign key constraint Sample_type mediumint(5) UNSIGNED NOT NULL,Īssay mediumint(5) UNSIGNED ZEROFILL NOT NULL, So referential integrity is established, but I want to enforce it. They both contain integers that are identical to the primary keys in two other tables. The particular table in question has two columns. | inserted_by | int(11) unsigned | YES | MUL | NULL | |Īnd I wan't to create a new table called sample_df referencing this, using the following: CREATE TABLE sample_df (ĭf_id mediumint(5) UNSIGNED AUTO_INCREMENT PRIMARY KEY, How do you create a foreign key in the foreign keys tab There is an Add button there, but I don't know how to use it. | Initials | varchar(255) | NO | | NULL | | | EID | varchar(45) | NO | PRI | NULL | | | Field | Type | Null | Key | Default | Extra | I'm having some problems creating a foreign key to an existing table in a MySQL database.
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