CREATE TABLE vendor (

    id INT PRIMARY KEY AUTO_INCREMENT

);

INSERT INTO vendor (id) VALUES (1), (2), (3);

CREATE TABLE customer_X (

    id INT PRIMARY KEY AUTO_INCREMENT,

    vendor_id INT NOT NULL,

    is_active BOOLEAN

);

ALTER TABLE `customer_X`

  ADD CONSTRAINT `customer_X_ibfk_1` FOREIGN KEY (`vendor_id`) REFERENCES `vendor` (`id`);

CREATE TABLE customer_base (

    id INT PRIMARY KEY AUTO_INCREMENT,

    vendor_id INT NOT NULL,

    is_active BOOLEAN

);

ALTER TABLE `customer_base`

  ADD CONSTRAINT `customer_base_ibfk_1` FOREIGN KEY (`vendor_id`) REFERENCES `vendor` (`id`);

INSERT INTO customer_X (vendor_id, is_active) VALUES (1, 1), (2, 0), (3, 1);

CREATE TRIGGER cbbi

BEFORE INSERT ON customer_base

FOR EACH ROW

BEGIN

    IF FALSE THEN SET @x = 1; END IF;

END;

INSERT INTO customer_base (id, vendor_id, is_active) (SELECT id, vendor_id, is_active FROM customer_X);