SQL Syntax Error (phpMyAdmin) - php

Question

What's wrong with this SQL statement:
ALTER TABLE `tbl_issue`
ADD CONSTRAINT `FK_issue_requester`
FOREIGN KEY (`requester_id`) REFERENCES `tbl_user` (`id`) ON DELETE CASCADE ON UPDATE RESTRICT;
I have tables called tbl_issue and tbl_user within a database called trackstar_dev.
phpMyAdmin said:
#1005 - Can't create table 'trackstar_dev.#sql-1a4_9d' (errno: 121) (Details...)

Answer 1

The most common reason for this error is that the foreign key constraint have the same name as in another table. Foreign keys' names must be unique in the database (not just on table level). Do you have requester_id in another table in your database?

Answer 2

you will get this message if you're trying to add a constraint with a name that's already used somewhere else, c you will get this message if you're trying to add a constraint with a name that's already used somewhere else . change it and it will be ok :)

Answer 3

I had this same problem. Drop all the tables in your database and then use the SQL code below to recreate them. I assume you are following the example in the agile web development with Yii 1.1 and php 5
- Disable foreign keys
SET FOREIGN_KEY_CHECKS = 0 ;# MySQL returned an empty result set (i.e. zero rows).
-- Create tables section -------------------------------------------------
-- Table tbl_project
CREATE TABLE IF NOT EXISTS `tbl_project` (
`id` INTEGER NOT NULL auto_increment,
`name` varchar(128) NOT NULL,
`description` text NOT NULL,
`create_time` DATETIME default NULL,
`create_user_id` INTEGER default NULL,
`update_time` DATETIME default NULL,
`update_user_id` INTEGER default NULL,
PRIMARY KEY (`id`)
) ENGINE = InnoDB
;# MySQL returned an empty result set (i.e. zero rows).
-- DROP TABLE IF EXISTS `tbl_issue` ;
CREATE TABLE IF NOT EXISTS `tbl_issue`
(
`id` INTEGER NOT NULL PRIMARY KEY AUTO_INCREMENT,
`name` varchar(256) NOT NULL,
`description` varchar(2000),
`project_id` INTEGER,
`type_id` INTEGER,
`status_id` INTEGER,
`owner_id` INTEGER,
`requester_id` INTEGER,
`create_time` DATETIME,
`create_user_id` INTEGER,
`update_time` DATETIME,
`update_user_id` INTEGER
) ENGINE = InnoDB
;# MySQL returned an empty result set (i.e. zero rows).
-- DROP TABLE IF EXISTS `tbl_user` ;
-- Table User
CREATE TABLE IF NOT EXISTS `tbl_user`
(
`id` INTEGER NOT NULL PRIMARY KEY AUTO_INCREMENT,
`email` Varchar(256) NOT NULL,
`username` Varchar(256),
`password` Varchar(256),
`last_login_time` Datetime,
`create_time` DATETIME,
`create_user_id` INTEGER,
`update_time` DATETIME,
`update_user_id` INTEGER
) ENGINE = InnoDB
;# MySQL returned an empty result set (i.e. zero rows).
-- DROP TABLE IF EXISTS `tbl_project_user_assignment` ;
-- Table User
CREATE TABLE IF NOT EXISTS `tbl_project_user_assignment`
(
`project_id` Int(11) NOT NULL,
`user_id` Int(11) NOT NULL,
`create_time` DATETIME,
`create_user_id` INTEGER,
`update_time` DATETIME,
`update_user_id` INTEGER,
PRIMARY KEY (`project_id`,`user_id`)
) ENGINE = InnoDB
;# MySQL returned an empty result set (i.e. zero rows).
-- The Relationships
ALTER TABLE `tbl_issue` ADD CONSTRAINT `FK_issue_project` FOREIGN KEY (`project_id`) REFERENCES `tbl_project` (`id`) ON DELETE CASCADE ON UPDATE RESTRICT;# MySQL returned an empty result set (i.e. zero rows).
ALTER TABLE `tbl_issue` ADD CONSTRAINT `FK_issue_owner` FOREIGN KEY (`owner_id`) REFERENCES `tbl_user` (`id`) ON DELETE CASCADE ON UPDATE RESTRICT;# MySQL returned an empty result set (i.e. zero rows).
ALTER TABLE `tbl_issue` ADD CONSTRAINT `FK_issue_requester` FOREIGN KEY (`requester_id`) REFERENCES `tbl_user` (`id`) ON DELETE CASCADE ON UPDATE RESTRICT;# MySQL returned an empty result set (i.e. zero rows).
ALTER TABLE `tbl_project_user_assignment` ADD CONSTRAINT `FK_project_user` FOREIGN KEY (`project_id`) REFERENCES `tbl_project` (`id`) ON DELETE CASCADE ON UPDATE RESTRICT;# MySQL returned an empty result set (i.e. zero rows).
ALTER TABLE `tbl_project_user_assignment` ADD CONSTRAINT `FK_user_project` FOREIGN KEY (`user_id`) REFERENCES `tbl_user` (`id`) ON DELETE CASCADE ON UPDATE RESTRICT;# MySQL returned an empty result set (i.e. zero rows).
-- Insert some seed data so we can just begin using the database
INSERT INTO `tbl_user`
(`email`, `username`, `password`)
VALUES
('test1#notanaddress.com','Test_User_One', MD5('test1')),
('test2#notanaddress.com','Test_User_Two', MD5('test2'))
;# 2 rows affected.
-- Enable foreign keys
SET FOREIGN_KEY_CHECKS = 1 ;# MySQL returned an empty result set (i.e. zero rows).