Answers for "drop foreign key mysql"

SQL

mysql add foreign key

-- On Create
CREATE TABLE tableName (
    ID INT,
    SomeEntityID INT,
    PRIMARY KEY (ID),
    FOREIGN KEY (SomeEntityID)
        REFERENCES SomeEntityTable(ID)
        ON DELETE CASCADE
);

-- On Alter, if the column already exists but has no FK
ALTER TABLE
  tableName
ADD
  FOREIGN KEY (SomeEntityID) REFERENCES SomeEntityTable(ID) ON DELETE CASCADE;
  
 -- Add FK with a specific name
 -- On Alter, if the column already exists but has no FK
ALTER TABLE
  tableName
ADD CONSTRAINT fk_name
  FOREIGN KEY (SomeEntityID) REFERENCES SomeEntityTable(ID) ON DELETE CASCADE;

Posted by: Guest on April-27-2020

mysql remove foreign key constraint

ALTER TABLE jobs DROP FOREIGN KEY constraint_name

Posted by: Guest on August-08-2020

drop all foreign key constraints mysql

SET foreign_key_checks = 0;

Posted by: Guest on June-26-2020

Source

foreign key mySql

CREATE TABLE parent (
    id INT NOT NULL,
    PRIMARY KEY (id)
) ENGINE=INNODB;

CREATE TABLE child (
    id INT,
    parent_id INT,
    INDEX par_ind (parent_id),
    FOREIGN KEY (parent_id)
        REFERENCES parent(id)
        ON DELETE CASCADE
) ENGINE=INNODB;

Posted by: Guest on March-02-2020

Source

add column mysql with foreign key

ALTER TABLE `TABLE_NAME`
ADD COLUMN `COLUMN_NAME` BIGINT(20) UNSIGNED NULL DEFAULT NULL AFTER `AFTER_COLUMN_NAME`, 
ADD FOREIGN KEY `FOREIGN_RELATION_NAME`(`COLUMN_NAME`) REFERENCES `FOREIGN_TABLE`(`FOREIGN_COLUMN`)  ON UPDATE SET NULL ON DELETE SET NULL

Posted by: Guest on December-24-2020

drop foreign key mysql

ALTER TABLE table_name DROP FOREIGN KEY constraint_name

Posted by: Guest on September-06-2021

Source

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