How to use Foreign key in SQL statements?

Question

I’m wanting to use Foreign key but I’m not getting it. This instruction SQL will create a table called tbl_estado with 4 columns id, nome, uf, pais and in the column pais will enter the key Foreign that will be searched in tbl_pais the id of the country which is the column id.

$where = axitech20 (bank)

$tablep = tbl_pais

$tableet = tbl_estado

$sql8   = "CREATE TABLE IF NOT EXISTS $aonde.$tablee (
            id INT(6) UNSIGNED ZEROFILL NOT NULL AUTO_INCREMENT PRIMARY KEY,
            nome        VARCHAR(75) DEFAULT NULL,
            uf          VARCHAR(5) DEFAULT NULL,
            pais        INT(6) DEFAULT NULL KEY '??????????' ($tablep)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=28";

I’m not getting to do the relationship that’s something in there ?????????? of the instruction. Can help me to hit the foreign key?

Answer 1

That way it should work:

CREATE TABLE axitech20.tb1_pais (
    id INT NOT NULL PRIMARY KEY AUTO_INCREMENT
);

CREATE TABLE axitech20.tbl_estado (
    id INT NOT NULL PRIMARY KEY AUTO_INCREMENT,
    id_pais INT NOT NULL,
    nome VARCHAR(75),
    uf VARCHAR(5),
    FOREIGN KEY (id_pais) REFERENCES tb1_pais(id)
);