SQL 大小写表达式（有条件）

Question

This is my CASE Expression:

case when count(distinct fcia.UserKey) > 1 and dd.FullDate between @CalcDate and @DefaultDate 
            then count(distinct fcia.UserKey)
else case when count(distinct fcia.UserKey) > 1 and dd.FullDate not between @CalcDate and @DefaultDate 
            then 0
else -1
end
end as StudentCount,

I would like to only display 1 condition, for example:

If the count > 1 and between the two dates then display

If the count > 1 and NOT BETWEEN dates then ONLY display if not equal to the above condition.

Lastly, else -1 if both conditions above do not equate.

Answer 1

Your current attempt is close. The correct syntax is:

CASE WHEN (condition1) THEN ... WHEN (condition2) THEN ... ELSE ... END

So use this CASE statement:

CASE WHEN COUNT(DISTINCT fcia.UserKey) > 1 AND
          dd.FullDate BETWEEN @CalcDate AND @DefaultDate 
     THEN COUNT(DISTINCT fcia.UserKey)
     WHEN COUNT(DISTINCT fcia.UserKey) > 1 AND
          dd.FullDate NOT BETWEEN @CalcDate AND @DefaultDate 
     THEN 0
     ELSE -1
END AS StudentCount