MySQL Update a table by min of another table - mysql

Question

I would like to update Table Lease from Table History
CREATE TABLE Lease
(`LeaseID` int, `Name` varchar(3), `Users` varchar(15), `WhoSignID` int, `NoteDate` date)
;
INSERT INTO Lease
(`LeaseID`, `Name`, `Users`, `WhoSignID`, `NoteDate`)
VALUES
(1, 'AAA', '1000,1001', NULL, NULL),
(2, 'BBB', '1002', NULL, NULL),
(3, 'CCC', '1003,1004', NULL, NULL),
(4, 'DDD', '1005,1006, 1007', NULL, NULL)
;
CREATE TABLE History
(`HistoryID` int, `LeaseID` int, `User` int, `SignDate` date)
;
INSERT INTO History
(`HistoryID`, `LeaseID`, `User`, `SignDate`)
VALUES
(1, 1, 1000, '2020-01-05'),
(2, 1, 1001, '2020-01-04'),
(3, 1, 1001, '2020-01-02'),
(4, 1, 1000, '2020-01-03'),
(6, 2, 1002, '2020-05-01'),
(7, 2, 1002, '2020-05-03')
;
I looking of a Mysql Update to update Table Lease :
NoteDate and WhoSignID based on SignDate and User
where Minimum of SignDate of User
Table Lease After Update
LeaseID | Name | Users | WhoSignID | NoteDate
1 | AAA | 1000,1001 | 1001 | 2020-01-02
2 | BBB | 1002 | 1002 | 2020-05-01
...
I appreciate any assist

Answer 1

Your Lease table has a serious design problem, because it is storing users as a CSV list. Instead, you should have each user value on a separate record. That being said, it appears that the CSV user list is immaterial to your current problem, which only required finding the earliest date for each lease. If so, then a simple update join should suffice:
UPDATE Lease l
INNER JOIN
(
SELECT h1.LeaseID, h1.User, h2.MinSignDate
FROM History h1
INNER JOIN
(
SELECT LeaseID, MIN(SignDate) AS MinSignDate
FROM History
GROUP BY LeaseID
) h2
ON h2.LeaseID = h1.LeaseID AND
h2.MinSignDate = h1.SignDate
) h
ON h.LeaseID = l.LeaseID
SET
WhoSignID = h.User,
NoteDate = h.MinSignDate;