MySQL 8.0

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CREATE TABLE receipts (id  int, 	`date`date, 	supplier varchar(10),	total DECIMAL(10,2))
INSERT INTO receipts VALUES (1,NOW(),'a',100.1),(2,NOW(),'b',200.2)
CREATE TABLE parts (id 	int, receipt_id 	int , partType varchar(10), 	subtotal DECIMAL(10,2))
INSERT INTO parts VALUEs (1,1,'a',20.0),(2,1,'a',20.0),(3,1,'a',20.1),(4,1,'a',20.0),(2,1,'a',20.0),
(6,2,'a',50.0),(7,2,'a',150.0)
SELECT 
    r.*
FROM
    receipts r
WHERE
    (SELECT 
            SUM(parts.subtotal)
        FROM
            parts
        WHERE
            receipt_id = r.id) != r.total;


id
date
supplier
total


2
2021-06-17
b
200.20


 SELECT 
    r.* ,  (SELECT 
            SUM(parts.subtotal)
        FROM
            parts
        WHERE
            receipt_id = r.id) sumsubtotal
 FROM
    receipts r
            


id
date
supplier
total
sumsubtotal


1
2021-06-17
a
100.10
100.10

2
2021-06-17
b
200.20
200.00