带有左联接和分组依据的MySQL Update查询

我认为这

(Index1, Index2)

Table

t.SpecialEventCount

编辑查询以使用子查询，因为它无法使用

GROUP BY

UPDATe    Table AS t    LEFT JOIN (        SELECT Index1, Index2, COUNT(EventType) AS NumEvents        FROM MEvents        WHERe EventType = 'A' OR EventType = 'B'        GROUP BY Index1, Index2    ) AS m ON        m.Index1 = t.Index1 AND        m.Index2 = t.Index2SET    t.SpecialEventCount = m.NumEventsWHERe    t.SpecialEventCount IS NULL