add new foreign key column mysql code example
Example 1: alter table add foreign key mysql
ALTER TABLE orders
ADD
FOREIGN KEY (user_id) REFERENCES users(id) ON DELETE CASCADE;
Example 2: mysql add foreign key
CREATE TABLE tableName (
ID INT,
SomeEntityID INT,
PRIMARY KEY (ID),
FOREIGN KEY (SomeEntityID)
REFERENCES SomeEntityTable(ID)
ON DELETE CASCADE
);
ALTER TABLE
tableName
ADD
FOREIGN KEY (SomeEntityID) REFERENCES SomeEntityTable(ID) ON DELETE CASCADE;
ALTER TABLE
tableName
ADD CONSTRAINT fk_name
FOREIGN KEY (SomeEntityID) REFERENCES SomeEntityTable(ID) ON DELETE CASCADE;
Example 3: mysql alter add foreign key
ALTER TABLE ordenes ADD ticket VARCHAR(50) NOT NULL;
ALTER TABLE ordenes ADD CONSTRAINT fk_ticket FOREIGN KEY (ticket) REFERENCES tickets(ticket);