Error Code: 1215. Cannot add foreign key constraint - mysql

Question

I'm trying to create a software for a gym but I'm getting this error and I don't know why, I've trying for hours but nothing
CREATE TABLE Socios (
IdSocio INT NOT NULL AUTO_INCREMENT,
Nombre VARCHAR(30) NOT NULL,
Apellido VARCHAR(30) NOT NULL,
N_Celular VARCHAR(12),
Correo VARCHAR(60),
Fecha_Nacimiento DATE NOT NULL,
Fecha_Asociacion DATE NOT NULL,
Fecha_Modificacion DATE NOT NULL,
Notas VARCHAR(100),
PRIMARY KEY (IdSocio)
) ENGINE=INNODB;
CREATE TABLE tipos(
IdTipos INT NOT NULL AUTO_INCREMENT,
Tipo VARCHAR (30) NOT NULL,
Precio DECIMAL(6,2) NOT NULL,
PRIMARY KEY (IdTipos)
) ENGINE = INNODB;
CREATE TABLE productos (
IdProducto INT NOT NULL AUTO_INCREMENT,
Producto VARCHAR (40) NOT NULL,
Descripcion VARCHAR (100),
Costo_Individual DECIMAL(6,2) NOT NULL,
Precio_venta DECIMAL(6,2) NOT NULL,
Estado BOOL NOT NULL,
Cantidad_Inicial INT NOT NULL,
Cantidad_actual INT NOT NULL,
PRIMARY KEY(IdProducto)
) ENGINE = INNODB;
Error Code: 1215. Cannot add foreign key constraint
I'm getting this error for this tables
CREATE TABLE membresia(
IdMembresia INT NOT NULL AUTO_INCREMENT,
Nombre VARCHAR(30) NOT NULL,
Tipo VARCHAR(30) NOT NULL,
Fecha_Inicio DATE NOT NULL,
Fecha_Vencimiento DATE NOT NULL,
Inscripcion BOOL NOT NULL,
Estado_membresia VARCHAR(15) NOT NULL,
Fecha_modificacion DATE NOT NULL,
Total DECIMAL(6,2) NOT NULL,
Nota VARCHAR(100),
Fecha_Nota DATE,
PRIMARY KEY (IdMembresia),
CONSTRAINT IdSocio FOREIGN KEY (Nombre)
REFERENCES Socios (Nombre),
CONSTRAINT IdTipos FOREIGN KEY (Tipo,Total)
REFERENCES tipos (Tipo,Precio)
) ENGINE = INNODB;
CREATE TABLE ventas (
IdVenta INT NOT NULL AUTO_INCREMENT,
Producto VARCHAR (40) NOT NULL,
Fecha_venta DATE NOT NULL,
cantidad INT NOT NULL,
Total DECIMAL(8,2),
Fecha_Modificacion DATE NOT NULL,
Nota VARCHAR (100),
PRIMARY KEY (IdVenta),
CONSTRAINT IdProducto FOREIGN KEY (Producto)
REFERENCES productos(Producto)
) ENGINE = INNODB;

Answer 1

This will get you over an initial hurdle. Though I doubt you really want an FK on a price but I don't know the translation into your mother tongue.
You need indexes on the referenced tables for the columns looked up in FK's.
create schema dbtest_xyz;
use dbtest_xyz;
-- drop table Socios;
CREATE TABLE Socios (
IdSocio INT NOT NULL AUTO_INCREMENT,
Nombre VARCHAR(30) NOT NULL,
Apellido VARCHAR(30) NOT NULL,
N_Celular VARCHAR(12),
Correo VARCHAR(60),
Fecha_Nacimiento DATE NOT NULL,
Fecha_Asociacion DATE NOT NULL,
Fecha_Modificacion DATE NOT NULL,
Notas VARCHAR(100),
PRIMARY KEY (IdSocio),
key(Nombre) -- ADDED *******************************
) ENGINE=INNODB;
-- drop table tipos;
CREATE TABLE tipos(
IdTipos INT NOT NULL AUTO_INCREMENT,
Tipo VARCHAR (30) NOT NULL,
Precio DECIMAL(6,2) NOT NULL,
PRIMARY KEY (IdTipos),
key(Tipo), -- ADDED *******************************
key(Precio) -- ADDED *******************************
) ENGINE = INNODB;
-- drop table productos;
CREATE TABLE productos (
IdProducto INT NOT NULL AUTO_INCREMENT,
Producto VARCHAR (40) NOT NULL,
Descripcion VARCHAR (100),
Costo_Individual DECIMAL(6,2) NOT NULL,
Precio_venta DECIMAL(6,2) NOT NULL,
Estado BOOL NOT NULL,
Cantidad_Inicial INT NOT NULL,
Cantidad_actual INT NOT NULL,
PRIMARY KEY(IdProducto),
key(Producto) -- ADDED *******************************
) ENGINE = INNODB;
CREATE TABLE membresia(
IdMembresia INT NOT NULL AUTO_INCREMENT,
Nombre VARCHAR(30) NOT NULL,
Tipo VARCHAR(30) NOT NULL,
Fecha_Inicio DATE NOT NULL,
Fecha_Vencimiento DATE NOT NULL,
Inscripcion BOOL NOT NULL,
Estado_membresia VARCHAR(15) NOT NULL,
Fecha_modificacion DATE NOT NULL,
Total DECIMAL(6,2) NOT NULL,
Nota VARCHAR(100),
Fecha_Nota DATE,
PRIMARY KEY (IdMembresia),
CONSTRAINT IdSocio FOREIGN KEY (Nombre)
REFERENCES Socios (Nombre),
CONSTRAINT IdTipos FOREIGN KEY (Tipo)
REFERENCES tipos (Tipo),
CONSTRAINT IdMembresia FOREIGN KEY (Total)
REFERENCES tipos (Precio)
) ENGINE = INNODB;
CREATE TABLE ventas (
IdVenta INT NOT NULL AUTO_INCREMENT,
Producto VARCHAR (40) NOT NULL,
Fecha_venta DATE NOT NULL,
cantidad INT NOT NULL,
Total DECIMAL(8,2),
Fecha_Modificacion DATE NOT NULL,
Nota VARCHAR (100),
PRIMARY KEY (IdVenta),
CONSTRAINT IdProducto FOREIGN KEY (Producto)
REFERENCES productos(Producto)
) ENGINE = INNODB;
-- Cleanup:
drop schema dbtest_xyz;
Mysql Manual Page on Foreign Keys
MySQL requires indexes on foreign keys and referenced keys so that
foreign key checks can be fast and not require a table scan. In the
referencing table, there must be an index where the foreign key
columns are listed as the first columns in the same order. Such an
index is created on the referencing table automatically if it does not
exist. This index might be silently dropped later, if you create
another index that can be used to enforce the foreign key constraint.
index_name, if given, is used as described previously.
Note, the reason I have the drop tables above some tables is that it is wise to have them in place while one iteratively attempts the creations. When the FK creations fail, one often (almost always) has to re-jigger the referenced and referencing tables.

Answer 2

Your first 2 tables should be as per below, means referenced fields should be indexed.
CREATE TABLE Socios (
IdSocio INT NOT NULL AUTO_INCREMENT,
Nombre VARCHAR(30) NOT NULL,
Apellido VARCHAR(30) NOT NULL,
N_Celular VARCHAR(12),
Correo VARCHAR(60),
Fecha_Nacimiento DATE NOT NULL,
Fecha_Asociacion DATE NOT NULL,
Fecha_Modificacion DATE NOT NULL,
Notas VARCHAR(100),
KEY idx_Nombre(Nombre),
PRIMARY KEY (IdSocio)
) ENGINE=INNODB;
CREATE TABLE tipos(
IdTipos INT NOT NULL AUTO_INCREMENT,
Tipo VARCHAR (30) NOT NULL,
Precio DECIMAL(6,2) NOT NULL,
KEY idx_tipo_precio(Tipo,Precio),
PRIMARY KEY (IdTipos)
) ENGINE = INNODB;

Answer 3

In case this may help someone else one day, I had this issue yet none of the existing solutions helped - columns were same type, same collation, etc.
However, I had a stored generated column in the table containing the foreign key that referenced that key column, and for some reason this broke the foreign key generation. Removing the generated column and using a trigger instead fixed it.