My 'ON DELETE CASCADE ' does not work

问题

I have got 3 tables: lt_hdefaults, lt_hperiods and lt_hrules. In lt_hdefaults, there is one row for a property for a particular year. In the lt_hperiods table, there could be more than one period, call them seasons. In the lt_hrules table, there could be more than one rule for each period. Now, what I could not make work: when the user deletes a record from lt_hdefaults, other data related to the deleted record should be removed from lt_hperiods and lt_hrules table. I am trying to achieve this by using

FOREIGN KEY (lt_year,lt_id) REFERENCES lt_hdefaults(lt_year,lt_id) ON DELETE CASCADE

However, it does not work. I know it looks long but it's not very complicated. If anyone has any idea, I would appreciate it. I know how to use mysql however I am not an expert on that. Thanks very much.

Samples below:

CREATE TABLE IF NOT EXISTS lt_hdefaults (
  lt_year year(4) NOT NULL DEFAULT '0000',
  lt_id int(255) NOT NULL DEFAULT '0',
  period_name varchar(45) NOT NULL DEFAULT 'Default',
  min_stay int(10) NOT NULL DEFAULT '1',
  max_stay int(10) NOT NULL,
  weekly_rate float(10,2) NOT NULL,
  nightly_rate float(10,2) NOT NULL,
  PRIMARY KEY (lt_year,lt_id)
) ENGINE=MyISAM DEFAULT CHARSET=latin1;    

CREATE TABLE IF NOT EXISTS lt_hperiods (
  period_id int(255) NOT NULL ,
  lt_id int(255) NOT NULL,
  lt_year year(4) NOT NULL DEFAULT '0000',
  period_name varchar(45) NOT NULL,
  min_stay int(10) NOT NULL,
  max_stay int(10) NOT NULL,
  fromDate date NOT NULL,
  toDate date NOT NULL,
  weekly_rate float(10,2) DEFAULT NULL,
  nightly_rate float(10,2) NOT NULL,
  arriveDepartDays varchar(150) DEFAULT 'sunday,monday,tuesday,wednesday,thursday,friday,saturday',
  noArriveDepartDays varchar(150) DEFAULT NULL,
  PRIMARY KEY (period_id),
  FOREIGN KEY (lt_year,lt_id) REFERENCES lt_hdefaults(lt_year,lt_id) ON DELETE CASCADE
) ENGINE=MyISAM  DEFAULT CHARSET=latin1 AUTO_INCREMENT=107 ;    

CREATE TABLE IF NOT EXISTS lt_hrules (
  period_id int(255) NOT NULL,
  lt_id int(255) NOT NULL,
  lt_year year(4) NOT NULL DEFAULT '0000',
  rule_name varchar(45) NOT NULL,
  night_of_stay int(10) NOT NULL,
  fixed_rate float(10,2) NOT NULL,
  PRIMARY KEY (period_id,lt_id,night_of_stay),
  FOREIGN KEY (period_id) REFERENCES lt_hperiods(period_id) ON DELETE CASCADE
) ENGINE=MyISAM DEFAULT CHARSET=latin1;    

INSERT INTO lt_hdefaults (lt_year, lt_id, period_name, min_stay, max_stay, weekly_rate, nightly_rate, min_guests, max_guests, surchargeAboveGuests, chargePerGuestFee, bondFee, cleaningFee, bookingServiceFee) VALUES
(2010, 2, 'Default', 0, 0, 1200.00, 171.43, 2, 5, 6, 85.00, 1000.00, 120.00, 0.00),
(2010, 3, 'Default', 0, 0, 1300.00, 185.71, 2, 5, 6, 44.00, 1000.00, 120.00, 0.00);

INSERT INTO lt_hperiods (period_id, lt_id, lt_year, period_name, min_stay, max_stay, fromDate, toDate, weekly_rate, nightly_rate, arriveDepartDays, noArriveDepartDays) VALUES
(105, 3, 2010, 'winter', 2, 66, '2010-12-22', '2011-01-15', 1500.00, 214.29, 'Monday,Tuesday,Wednesday,Thursday', 'Friday,Saturday,Sunday'),
(106, 3, 2010, 'summer', 2, 77, '2011-01-14', '2011-01-28', 4000.00, 571.43, 'Monday,Tuesday,Wednesday,Thursday,Friday,Saturday', 'Sunday');

INSERT INTO lt_hrules (period_id, lt_id, lt_year, rule_name, night_of_stay, fixed_rate) VALUES
(106, 3, 2010, 'r2', 2, 222.00),
(106, 3, 2010, 'r1', 1, 111.00),
(105, 3, 2010, 'r2', 2, 222.00),
(105, 3, 2010, 'r1', 1, 111.00);

回答1:

ENGINE=MyISAM <-- MyISAM doesn't support any kind of foreign keys. Use InnoDB instead.

回答2:

for Foreign key referencing use innoDB

回答3:

Something like this works..as an example:

SET SQL_MODE="NO_AUTO_VALUE_ON_ZERO";

CREATE TABLE IF NOT EXISTS lt_hperiods ( 
    period_id          int(255)      NOT NULL,  
    lt_id              int(255)      NOT NULL,
    lt_year            year(4)       NOT NULL DEFAULT '0000',  
    period_name        varchar(45)   NOT NULL,  
    min_stay           int(10)       NOT NULL,
    max_stay           int(10)       NOT NULL,   
    fromDate           date          NOT NULL,
    toDate             date          NOT NULL,  
    weekly_rate        float(10,2)   DEFAULT NULL, 
    nightly_rate       float(10,2)   NOT NULL,  
    arriveDepartDays   varchar(150)  DEFAULT 'sunday,monday,tuesday,wednesday,thursday,friday,saturday',
    noArriveDepartDays varchar(150)  DEFAULT NULL,

    PRIMARY KEY (period_id),
    INDEX (lt_id),
    INDEX (lt_year),
    CONSTRAINT FOREIGN KEY (`lt_id`, `lt_year`) 
    REFERENCES lt_hdefaults(`lt_id`, `lt_year`) ON DELETE CASCADE
) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=107;



SET SQL_MODE="NO_AUTO_VALUE_ON_ZERO";

CREATE TABLE IF NOT EXISTS lt_hrules (
    period_id      int(255)     NOT NULL,
    lt_id          int(255)     NOT NULL,
    lt_year        year(4)      NOT NULL DEFAULT '0000',
    rule_name      varchar(45)  NOT NULL,
    night_of_stay  int(10)      NOT NULL,
    fixed_rate     float(10,2)  NOT NULL,

    PRIMARY KEY (period_id,lt_id,night_of_stay),
    INDEX(period_id),
    CONSTRAINT FOREIGN KEY (`period_id`)
    REFERENCES lt_hperiods(`period_id`) ON DELETE CASCADE
) ENGINE=InnoDB  DEFAULT CHARSET=latin1;

来源：https://stackoverflow.com/questions/4506272/my-on-delete-cascade-does-not-work

标签

mysql

Cascade

cascading-deletes