SQL间歇性地不返回任何数据以响应LEFT JOIN

Question

I am trying to hunt down a bug in a SQL query but can't seem to get to the bottom of it. The query looks like this:

SELECT
    DATE(BT.DateCheckedIn) AS X,
    DAYOFWEEK(BT.DateCheckedIn) AS DayX,
    SUM(IR.QtyCheckedIn) AS C,
    AU.AdminUsername,
    AU.AdminFirstName,
    AU.AdminLastName,
    IF(BTE.ProdLogID IS NULL, 'No', 'Yes') AS Exclude
FROM
    buying_issuesreceived IR
    JOIN buying_transactions BT ON IR.TransactionID = BT.TransactionID
    JOIN adminusers AU ON BT.CheckedInByAdminUserID = AU.AdminUserID
    LEFT JOIN log_production_bt BTE
        ON DATE(BT.DateCheckedIn) = DATE(BTE.ProductionDate)
        AND BTE.ProductionSection = 'wtransactions'
        AND AU.AdminUsername = BTE.ProductionUsername
WHERE
    DATE(BT.DateCheckedIn) BETWEEN DATE  '2018-09-24' AND DATE  '2018-09-30'
GROUP BY
    DATE(BT.DateCheckedIn),
    AU.AdminUsername

When this query is run, it has about a 50/50 chance of returning the correct data or returning nothing at all. There is no error message. I know, or rather should say, am pretty certain, that the LEFT JOIN is the culprit because when I delete it from the code I stop getting empty tables, but can't, for the life of me, figure out why this query would return inconsistent results in the first place.

Answer 1

This sounds like a MySQL bug. As a workaround, you can use EXISTS with a correlated subquery.

SELECT
    DATE(BT.DateCheckedIn) AS X,
    DAYOFWEEK(BT.DateCheckedIn) AS DayX,
    SUM(IR.QtyCheckedIn) AS C,
    AU.AdminUsername,
    AU.AdminFirstName,
    AU.AdminLastName,    
    IF(EXISTS(
        SELECT 1
        FROM log_production_bt BTE
        WHERE 
            DATE(BT.DateCheckedIn) = DATE(BTE.ProductionDate)
            AND BTE.ProductionSection = 'wtransactions'
            AND AU.AdminUsername = BTE.ProductionUsername), 'NO', 'YES') AS Exclude
FROM
    buying_issuesreceived IR
    JOIN buying_transactions BT ON IR.TransactionID = BT.TransactionID
    JOIN adminusers AU ON BT.CheckedInByAdminUserID = AU.AdminUserID
WHERE
    DATE(BT.DateCheckedIn) BETWEEN DATE  '2018-09-24' AND DATE  '2018-09-30'
GROUP BY
    DATE(BT.DateCheckedIn),
    AU.AdminUsername