Question

I’m working on my first MySQL database for an assignment at my university. Unfortunately I’ve been stuck for a while trying to create the actual tables with foreign keys between them.

This is the error that the MySQL Workbench forward engineering wizard gives:

Executing SQL script in server

ERROR: Error 1005: Can't create table 'test.fremført' (errno: 150)    

CREATE  TABLE IF NOT EXISTS `Fremført` (    
  `Plate` VARCHAR(20) NOT NULL ,
  `Verk` VARCHAR(45) NOT NULL ,
  `Artist` VARCHAR(45) NOT NULL ,
  `Dato` DATE NULL ,
  PRIMARY KEY (`Plate`, `Verk`, `Artist`) ,
  INDEX `Fremført->Artist_idx` (`Artist` ASC) ,
  INDEX `Fremført->Spor_idx` (`Plate` ASC, `Verk` ASC) ,
  CONSTRAINT `Fremført->Artist`
    FOREIGN KEY (`Artist` )
    REFERENCES `Artist` (`ArtistNavn` )
    ON DELETE NO ACTION
    ON UPDATE NO ACTION,
  CONSTRAINT `Fremført->Spor`
    FOREIGN KEY (`Plate` , `Verk` )
    REFERENCES `Spor` (`Verk` , `Verk` )
    ON DELETE NO ACTION
    ON UPDATE NO ACTION)
ENGINE = InnoDB

Does anyone know what’s wrong with the above script, and if so have a solution?

Thanks!

edit:
This is the requested spor query

DROP TABLE IF EXISTS `Spor` ;
CREATE  TABLE IF NOT EXISTS `Spor` (
  `Plate` VARCHAR(45) NOT NULL ,
  `Verk` VARCHAR(45) NOT NULL ,
  `Spilletid` DECIMAL(3,2) NULL ,
  PRIMARY KEY (`Plate`, `Verk`) ,
  INDEX `Plate_idx` (`Plate` ASC) ,
  CONSTRAINT `Plate`
    FOREIGN KEY (`Plate` )
    REFERENCES `Plate` (`KatalogNr` )
    ON DELETE NO ACTION
    ON UPDATE NO ACTION)
ENGINE = InnoDB;



DROP TABLE IF EXISTS `Artist` ;
CREATE  TABLE IF NOT EXISTS `Artist` (
  `ArtistNavn` VARCHAR(30) NOT NULL ,
  `Artistcol` VARCHAR(45) NULL ,
  PRIMARY KEY (`ArtistNavn`) )
ENGINE = InnoDB;

Answer 1

errno150 is very often related to a mismatch between the data types of the primary and related column. They must match exactly, including character length.

I see a data type mismatch between Fremført.artist (VARCHAR(45)) and Artist.ArtistNavn (VARCHAR(30)). These must be the same for the FOREIGN KEY constraint to succeed.

CREATE  TABLE IF NOT EXISTS `Fremført` (    
  `Plate` VARCHAR(20) NOT NULL ,
  `Verk` VARCHAR(45) NOT NULL ,
  /* Must match the primary table VARCHAR(30) */
  `Artist` VARCHAR(30) NOT NULL ,
  `Dato` DATE NULL ,
  PRIMARY KEY (`Plate`, `Verk`, `Artist`) ,
  INDEX `Fremført->Artist_idx` (`Artist` ASC) ,
  INDEX `Fremført->Spor_idx` (`Plate` ASC, `Verk` ASC) ,
  CONSTRAINT `Fremført->Artist`
    FOREIGN KEY (`Artist` )
    REFERENCES `Artist` (`ArtistNavn` )
    ON DELETE NO ACTION
    ON UPDATE NO ACTION,
  CONSTRAINT `Fremført->Spor`
    FOREIGN KEY (`Plate` , `Verk` )
    /* Was this intentional, rather than (`Plate`, `Verk`)? */
    /* If not, you must also match the data type of `Plate` VARCHAR(20) to that of Spor.Plate VARCHAR(45) */
    REFERENCES `Spor` (`Verk` , `Verk` )
    ON DELETE NO ACTION
    ON UPDATE NO ACTION)
ENGINE = InnoDB

As noted above, if the constraint Fremført->Spor was intended to reference Spor (Plate , Verk ) instead of Spor (Verk , Verk ) as you have defined it, then you will also encounter an err150 due to the type mismatch between Spor.Plate and Fremført.Plate. Change Fremført.Plate to VARCHAR(45).