Error when If_Else used in triggers - mysql

Question

Please refer the below image
I want to create an After Insert trigger on Ongoing_Fees table where it updates the VAT table. However before it insert data to the VAT table, it should check whether the VAT field of the particular Portfolio is true. Ongoing_Fees table has the foreign key access to the Portfolio table, so it can access the related portfolio.
Below is what I have tried
DELIMITER $$
CREATE TRIGGER `Ongoing_Fees_AINS` AFTER INSERT ON `Ongoing_Fees` FOR EACH ROW
BEGIN
DECLARE `vat` Boolean;
`vat` = SELECT VAT from Portfolio WHERE Portfolio.idPortfolio = New.idPortfolio;
IF (`vat` == true) THEN
INSERT INTO VAT VALUES (100, current_Timestamp, New.idPortfolio, New.idOngoing_Fees)
END;
But of course, it has an error
#1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '= SELECT VAT from Portfolio WHERE Portfolio.idPortfolio = New.idPortfolio;

Answer 1

Try:
DELIMITER $$
CREATE TRIGGER `Ongoing_Fees_AINS` AFTER INSERT ON `Ongoing_Fees`
FOR EACH ROW
BEGIN
DECLARE `_vat` BOOL;
SET `_vat` := (SELECT `VAT` FROM `Portfolio` WHERE `Portfolio`.`idPortfolio` = NEW.`idPortfolio`);
IF (`_vat` = TRUE) THEN
INSERT INTO `VAT` (
`Amount`,
`current_timestamp`,
`Portfolio_idPortfolio`,
`Ongoing_Fees_idOngoing`
)
VALUES (
100,
CURRENT_TIMESTAMP(),
NEW.`idPortfolio`,
NEW.`idOngoing_Fees`
);
END IF;
END$$
DELIMITER ;
A shorter version:
DELIMITER $$
CREATE TRIGGER `Ongoing_Fees_AINS` AFTER INSERT ON `Ongoing_Fees`
FOR EACH ROW
BEGIN
INSERT INTO `VAT` (
`Amount`,
`current_timestamp`,
`Portfolio_idPortfolio`,
`Ongoing_Fees_idOngoing`
)
SELECT
100,
CURRENT_TIMESTAMP(),
NEW.`idPortfolio`,
NEW.`idOngoing_Fees`
FROM
DUAL
WHERE
TRUE = (SELECT
`VAT`
FROM
`Portfolio`
WHERE
`Portfolio`.`idPortfolio` = NEW.`idPortfolio`
);
END$$
DELIMITER ;