MySQL error #1215: Cannot add Foreign Key Constraint - mysql

Question

I'm trying to implement the tables shown in the picture:
this picture
(database scheme taken from http://www.databaseanswers.org/data_models/recipes/index.htm).
But I'm having problems with the Recipe_step_ingredients table. When adding foreign key constraints, I get error #1215 for the recipe_steps_id constraint (when not adding that constraint, I don't get the error and I can add the other two constraints).
Here is may command for creating the table:
CREATE TABLE recipe_step_ingredients (
recipe_id INTEGER,
step_number INTEGER,
ingredient_id INTEGER,
amount_required VARCHAR(128),
CONSTRAINT FOREIGN KEY (recipe_id) REFERENCES recipe_steps (recipe_id) ON DELETE CASCADE ON UPDATE CASCADE,
CONSTRAINT FOREIGN KEY (step_number) REFERENCES recipe_steps (step_number) ON DELETE CASCADE ON UPDATE CASCADE,
CONSTRAINT FOREIGN KEY (ingredient_id) REFERENCES ingredients (ingredient_id) ON DELETE CASCADE ON UPDATE CASCADE,
PRIMARY KEY (recipe_id, step_number, ingredient_id)
) ENGINE = INNODB
Anybody knows what could be the problem with it?
EDIT: Changed the code to match the naming conventions in the picture.
Also, here is the rest of the DDL I used:
CREATE TABLE recipes (
recipe_id INTEGER NOT NULL AUTO_INCREMENT,
recipe_name VARCHAR(128),
recipe_description VARCHAR(4096),
PRIMARY KEY (recipe_id),
INDEX (recipe_name)
) ENGINE = INNODB
CREATE TABLE recipe_steps (
recipe_id INTEGER,
step_number INTEGER,
instructions VARCHAR(4096),
CONSTRAINT FOREIGN KEY (recipe_id) REFERENCES recipes (recipe_id) ON DELETE CASCADE ON UPDATE CASCADE,
PRIMARY KEY (recipe_id, step_number)
) ENGINE = INNODB
CREATE TABLE ingredient_types (
ingredient_type_id INTEGER NOT NULL AUTO_INCREMENT,
ingredient_type_description VARCHAR(4096),
PRIMARY KEY (ingredient_type_id)
) ENGINE = INNODB
ALTER TABLE ingredient_types ADD COLUMN ingredient_type_name VARCHAR(128);
ALTER TABLE ingredient_types ADD INDEX(ingredient_type_name);
CREATE TABLE ingredients (
ingredient_id INTEGER NOT NULL AUTO_INCREMENT,
ingredient_type_id INTEGER,
ingredient_name VARCHAR(128),
CONSTRAINT FOREIGN KEY (ingredient_type_id) REFERENCES ingredient_types (ingredient_type_id) ON DELETE CASCADE ON UPDATE CASCADE,
PRIMARY KEY (ingredient_id),
INDEX (ingredient_name)
) ENGINE = INNODB
CREATE TABLE recipe_step_ingredients (
recipe_id INTEGER,
step_number INTEGER,
ingredient_id INTEGER,
amount_required VARCHAR(128),
CONSTRAINT FOREIGN KEY (recipe_id) REFERENCES recipe_steps (recipe_id) ON DELETE CASCADE ON UPDATE CASCADE,
CONSTRAINT FOREIGN KEY (step_number) REFERENCES recipe_steps (step_number) ON DELETE CASCADE ON UPDATE CASCADE,
CONSTRAINT FOREIGN KEY (ingredient_id) REFERENCES ingredients (ingredient_id) ON DELETE CASCADE ON UPDATE CASCADE,
PRIMARY KEY (recipe_id, step_number, ingredient_id)
) ENGINE = INNODB

Answer 1

Make sure that:
the foreign key references ALL the attributes of the key of the referenced relation (you cannot reference only some of them). SO if the key of R is (A,B), you should reference both A and B. You cannot reference only A or only B.
the attribute(s) you are referencing in a foreign key constraint is defined as UNIQUE or is the Primary key of the relation. In Mysql this can also be done by defining the attribute a KEY or UNIQUE KEY.
If you are referencing the primary key you don't need to indicate the name of the attribute after the table (the default is its primary key).
In your case,
make sure that the table recipe_steps has an attribute recipe_steps_id, and
this attribute is either UNIQUE KEY, KEY or the primary key of the relation
Also, make sure the corresponding index (for the key) has been created.