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CREATE TABLE grandparent (
id INT NOT NULL PRIMARY KEY
) ENGINE=InnoDB;
CREATE TABLE parent (
id INT NOT NULL PRIMARY KEY,
grandparent_id INT,
FOREIGN KEY (grandparent_id)
REFERENCES grandparent(id)
ON DELETE CASCADE
) ENGINE=InnoDB;
CREATE TABLE child (
id INT NOT NULL PRIMARY KEY,
parent_id INT,
FOREIGN KEY (parent_id)
REFERENCES parent(id)
ON DELETE CASCADE
) ENGINE=InnoDB;
INSERT INTO grandparent VALUES (1),(2);
INSERT INTO parent VALUES (1,1), (2,2);
INSERT INTO child VALUES (1,1), (2,2);
DELETE FROM grandparent WHERE id = 1;
SELECT COUNT(*) = 0 FROM parent WHERE grandparent_id = 1;
COUNT(*) = 0
1
SELECT COUNT(*) = 0 FROM child WHERE parent_id = 1;
COUNT(*) = 0
1
DROP TABLE child;
DROP TABLE parent;
DROP TABLE grandparent;
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