title: Cannot add foreign key constraint - MySQL ERROR 1215 (HY000)
body: <p>I am trying to create database for gym management system, but I can't figure out why I am getting this error. I've tried to search for the answer here, but I couldn't find it.</p>
  
  <pre><code>ERROR 1215 (HY000): Cannot add foreign key constraint
  
  CREATE TABLE sales(
      saleId int(100) NOT NULL AUTO_INCREMENT,
      accountNo int(100) NOT NULL,
      payName VARCHAR(100) NOT NULL,
      nextPayment DATE,
      supplementName VARCHAR(250),
      qty int(11),
      workoutName VARCHAR(100),
      sDate datetime NOT NULL DEFAULT NOW(),
      totalAmount DECIMAL(11,2) NOT NULL,
      CONSTRAINT PRIMARY KEY(saleId, accountNo, payName),
      CONSTRAINT FOREIGN KEY(accountNo) REFERENCES accounts(accountNo) ON DELETE CASCADE ON UPDATE CASCADE,
      CONSTRAINT FOREIGN KEY(payName) REFERENCES paymentFor(payName) ON DELETE CASCADE ON UPDATE CASCADE,
      CONSTRAINT FOREIGN KEY(supplementName) REFERENCES supplements(supplementName) ON DELETE CASCADE ON UPDATE CASCADE,
      CONSTRAINT FOREIGN KEY(workoutName) REFERENCES workouts(workoutName) ON DELETE CASCADE ON UPDATE CASCADE
  );
      ALTER TABLE sales AUTO_INCREMENT = 2001;
  </code></pre>
  
  <p>Here is the parent tables.</p>
  
  <pre><code>CREATE TABLE accounts(
      accountNo int(100) NOT NULL AUTO_INCREMENT,
      accountType VARCHAR(100) NOT NULL,
      firstName VARCHAR(50) NOT NULL,
      lastName VARCHAR(60) NOT NULL,
      birthdate DATE NOT NULL,
      gender VARCHAR(7),
      city VARCHAR(50) NOT NULL,
      street VARCHAR(50),
      cellPhone VARCHAR(10),
      emergencyPhone VARCHAR(10),
      email VARCHAR(150) NOT NULL,
      description VARCHAR(350),
      occupation VARCHAR(50),
      createdOn datetime NOT NULL DEFAULT NOW(),
      CONSTRAINT PRIMARY KEY(accountNo)
  );
      ALTER TABLE accounts AUTO_INCREMENT = 1001; 
  
  
  CREATE TABLE supplements(
      supplementId int(100) NOT NULL AUTO_INCREMENT,
      supplementName VARCHAR(250) NOT NULL,
      manufacture VARCHAR(100),
      description VARCHAR(150),
      qtyOnHand INT(5),
      unitPrice DECIMAL(11,2),
      manufactureDate DATE,
      expirationDate DATE,
      CONSTRAINT PRIMARY KEY(supplementId, supplementName)
  );
      ALTER TABLE supplements AUTO_INCREMENT = 3001;
  
  CREATE TABLE workouts(
      workoutId int(100) NOT NULL AUTO_INCREMENT,
      workoutName VARCHAR(100) NOT NULL,
      description VARCHAR(7500) NOT NULL,
      duration VARCHAR(30),
      CONSTRAINT PRIMARY KEY(workoutId, workoutName)
  );
      ALTER TABLE workouts AUTO_INCREMENT = 4001;
  
  
  
  CREATE TABLE paymentFor(
      payId int(100) NOT NULL AUTO_INCREMENT,
      payName VARCHAR(100) NOT NULL,
      amount DECIMAL(11,2),
      CONSTRAINT PRIMARY KEY(payId, payName)
  );
      ALTER TABLE paymentFor AUTO_INCREMENT = 5001;
  </code></pre>
  
  <p>Can you guys help me with this problem? Thanks.</p>