database logic
brief : ALTER TABLE A ADD CONSTRAINT id PRIMARY KEY (id) ALTER TABLE B ADD COLUMN a_id VARCHAR //add fkey in B as additional cols ALTER TABLE B ADD COLUMN a_id int //now create the fkey ref to agent table on address table alter table B ADD Foreign key(a_id) references A(id); // To obtain the generated constraint name of a table SHOW CREATE TABLE B; ALTER TABLE B DROP FOREIGN KEY b _ibfk_1; //to disable fkey checks. SET foreign_key_checks = 0/1;