ERROR CODE 1215 - You can not add the foreign key

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ERROR CODE 1215 - You can not add the foreign key

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#1 by (1 votes)

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Table 1:

Table2:

Command: ALTER TABLE extras ADD FOREIGN KEY (login) REFERENCES usuario(login);

Response: Error Code: 1215. Cannot add foreign key constraint

Can not find an index in the referenced table where the Referenced columns appear as the first columns, or the types columns in the table and the referenced table do not match the restriction. Note that the internal storage type of ENUM and SET has changed in

I can not identify the reason for the error. Can anyone help me?

Ps. as you can see, the two fields are of the same type (varchar (15))

Thank you so much

mysql sql modelagem back-end

asked by anonymous 11.12.2017 / 17:51

1 answer

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score 1 · Accepted Answer

It seems that its structure is correct, check if the table type is like InnoDB itself, they can be like MyISAM which does not allow FK creation, follow script that I created from your print and worked normally:

CREATE TABLE IF NOT EXISTS 'usuario' (
  'login' VARCHAR(15) NOT NULL,
  'nome' VARCHAR(40) NOT NULL,
  'senha' VARCHAR(10) NOT NULL,
  PRIMARY KEY ('login'))
ENGINE = InnoDB;


CREATE TABLE IF NOT EXISTS 'extras' (
  'idFunc' INT NULL,
  'login' VARCHAR(15) NOT NULL,
  'data' DATETIME NULL,
  'extra' TEXT NULL,
  INDEX 'fk_extras_usuario_idx' ('login' ASC),
  CONSTRAINT 'fk_extras_usuario'
    FOREIGN KEY ('login')
    REFERENCES 'usuario' ('login')
    ON DELETE NO ACTION
    ON UPDATE NO ACTION)
ENGINE = InnoDB;