您有一些语法问题：
第一个问题是：
CASE (WHEN
第二个问题是：
ELSE WHEN
现在应该可以正常运行：
SELECt DISTINCT R.[Column1] AS Person, SUM(CASE WHEN R.[Event] = 'Event1' THEN 1 ELSE NULLEND) AS Event1, (CASE WHEN L.[Column2] LIKE '%String1%' THEN 'String1' WHEN L.[Column2] LIKE '%String2%' THEN 'String2' WHEN L.[Column2] LIKE '%String3%' THEN 'String3' ELSE NULL END) AS NewColumnFROM [Database1].[dbo].[Table1] R LEFT JOIN [Database1].[dbo].[Table2] L ON R.[UniqueIdentifier] = L.[UniqueIdentifier]WHERe L.[Column2] LIKE '%String1%' OR L.[Column2] LIKE '%String2%' OR L.[Column2] LIKE '%String3%'GROUP BY R.[Column1], L.[Column2]ORDER BY R.[Event1] DESC;
