Question

I ran the following query in MySQL command line and the tables were created. But when I ran in XAMPP, I got an error “1005 – Can’t create table ‘zoneboard.work’ (errno: 150)”

My query is :

Create Table user (
   id_user INT (50)NOT NULL AUTO_INCREMENT ,
   email VARCHAR( 64 ) NOT NULL ,
   username VARCHAR( 16 ) NOT NULL ,
   password VARCHAR( 32 ) NOT NULL ,
   PRIMARY KEY ( id_user )
) ENGINE = InnoDB

CREATE TABLE work (
  id_user INT( 50 ) NOT NULL AUTO_INCREMENT ,
  task VARCHAR( 50 ) NOT NULL ,
  comments VARCHAR( 100 ) NOT NULL ,
  assignee VARCHAR( 16 ) NOT NULL ,
  priority VARCHAR( 50 ) NOT NULL ,
  status VARCHAR( 50 ) NOT NULL ,
  dataum1 VARCHAR( 50 ) NOT NULL ,
  dataum2 VARCHAR( 50 ) NOT NULL ,
  PRIMARY KEY ( id_user ),
  FOREIGN KEY(assignee) REFERENCES user(username)
) ENGINE = InnoDB 

Answer 1

CREATE TABLE USER (
   id_user INT (50)NOT NULL AUTO_INCREMENT ,
   email VARCHAR( 64 ) NOT NULL ,
   username VARCHAR( 16 ) NOT NULL ,
   PASSWORD VARCHAR( 32 ) NOT NULL ,
   PRIMARY KEY ( id_user, username ),
  INDEX(username)
) ENGINE = INNODB;

Parent table-user should have an index column(Here username should be indexed).
Refer: http://dev.mysql.com/doc/refman/5.5/en/innodb-foreign-key-constraints.html

InnoDB permits a foreign key to reference any index column or group of columns. However, in the referenced table, there must be an index where the referenced columns are listed as the first columns in the same order.