Joining a single row to a query - mysql

Question

I need to get a value from another table but where there may be 5/6 results, I only need to show the latest one. I've tried the following:
SELECT s.Mileage
, s.PurchasePrice
, v.make
, v.model
, v.vrm
, c.CleanLive
FROM StockBook s
LEFT
JOIN Vehicles v
ON v.VehicleID = s.VehicleID
LEFT
JOIN CapVals c
ON c.LeadID = (SELECT C1.CleanLive
FROM CapVals C1
WHERE s.LeadID = c.LeadID
ORDER
BY C1.Date
LIMIT 1
)
ORDER
BY StockBookID
Which is working as a query but not showing CleanLive value.
I've set up a sample data set and DB Fiddle here:
CREATE TABLE `Vehicles` (
`VehicleID` int(11) NOT NULL,
`vrm` varchar(15) NOT NULL,
`make` varchar(40) NOT NULL,
`model` varchar(40) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
CREATE TABLE `StockBook` (
`StockBookID` int(11) NOT NULL,
`VehicleID` int(11) NOT NULL,
`LeadID` int(11) NOT NULL,
`Mileage` int(11) NOT NULL,
`PurchasePrice` decimal(15,2) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
CREATE TABLE `CapVals` (
`CapValsID` int(11) NOT NULL,
`LeadID` int(11) DEFAULT NULL,
`CleanLive` int(11) DEFAULT NULL,
`Date` datetime DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
INSERT INTO `Vehicles` (`VehicleID`, `vrm`, `make`, `model`) VALUES
(1, 'M900WRD', 'Vauxhall', 'Signum');
INSERT INTO `StockBook` (`StockBookID`, `LeadID`, `VehicleID`, `Mileage`, `PurchasePrice`) VALUES
(1, 1, 1, 17000, 15000.00);
INSERT INTO `CapVals` (`CapValsID`, `LeadID`, `CleanLive`, `Date`) VALUES
(6455, 1, 1540, '2019-12-04 15:02:29'),
(6456, 1, 1540, '2019-12-04 15:02:29'),
(6457, 1, 1540, '2019-12-04 15:02:29');
https://www.db-fiddle.com/f/b4fQuMVpXHGxqgYJ4ia92w/4

Answer 1

You can try this
SELECT Stock.Mileage, Stock.PurchasePrice, Vehi.make, Vehi.model, Vehi.vrm,
(SELECT CleanLive from CapVals a WHERE a.LeadID = Stock.LeadID ORDER BY DATE DESC LIMIT 1) AS CleanLive
FROM StockBook Stock
LEFT JOIN Vehicles Vehi
ON Stock.VehicleID=Vehi.VehicleID
ORDER BY StockBookID

Answer 2

SELECT v.vehicleID
, v.vrm
, v.make
, v.model
, s.stockbookid
, s.leadid
, s.mileage
, s.purchaseprice
, c.capvalsid
, c.cleanlive
, c.date
FROM vehicles v
JOIN stockbook s
ON s.vehicleid = v.vehicleid
JOIN capvals c
ON c.leadid = s.leadid
JOIN
( SELECT leadid,MAX(capvalsid) capvalsid FROM capvals GROUP BY leadid ) x
ON x.leadid = c.leadid
AND x.capvalsid = c.capvalsid;
+-----------+---------+----------+--------+-------------+--------+---------+---------------+-----------+-----------+---------------------+
| vehicleID | vrm | make | model | stockbookid | leadid | mileage | purchaseprice | capvalsid | cleanlive | date |
+-----------+---------+----------+--------+-------------+--------+---------+---------------+-----------+-----------+---------------------+
| 1 | M900WRD | Vauxhall | Signum | 1 | 1 | 17000 | 15000.00 | 6457 | 1540 | 2019-12-04 15:02:29 |
+-----------+---------+----------+--------+-------------+--------+---------+---------------+-----------+-----------+---------------------+

Answer 3

Use Row_number concept, which will avoid the duplicate rows and give you recent one,
FIDDLE DEMO
SELECT Stock.Mileage, Stock.PurchasePrice, Vehi.make, Vehi.model, Vehi.vrm,
X.CleanLive as CleanLive
FROM StockBook Stock
LEFT JOIN Vehicles Vehi ON Stock.VehicleID=Vehi.VehicleID
LEFT JOIN (SELECT #LeadID:=LeadID,C1.LeadID, CleanLive, C1.Date, #row_number:=CASE WHEN #LeadID = LeadID THEN #row_number + 1 ELSE 1 END AS num
FROM CapVals AS C1, (SELECT #LeadID:=0,#row_number:=0) as t ORDER BY C1.Date DESC) X ON X.LeadID = Stock.LeadID AND X.num = 1
ORDER BY StockBookID