Question

I’m having trouble trying to calculate a running total from within a CASE statement.
I have two tables @report and @question and two variables @countCurrent and @countSuggested.

Based off the numbers in the @report table compared against either a static value or a value from the @question table I need to increment either @countCurrent or @countSuggested.

Here is what I have so far but instead of getting some combination of 5 in either column, I am only getting 0/1. I think it is part of the JOIN but I can’t see what.

declare @MinSuccessRate float,
        @countCurrent int,
        @countSuggested int

declare @report table
(
    intID   int identity(1,1),
    intReportID int,
    intParticipantID int,
    acceptable float,
    optimum float
)
insert @report
    select 1,1,.25,.75 union all
    select 1,2,.45,.75 union all
    select 1,3,.35,.75 union all
    select 1,4,.55,.75 union all
    select 1,5,.65,.75

declare @question table
(
    intID   int identity(1,1),
    intParticipantID    int,
    answer  float
)

insert @question
select 1,35 union all
select 1,55 union all
select 1,65 union all
select 1,75 union all
select 1,85

SET @MinSuccessRate=0.75
SET @countCurrent=0
SET @countSuggested=0

UPDATE @report
SET @countCurrent= 
    CASE WHEN acceptable>=@MinSuccessRate 
        THEN @countCurrent+1 
        ELSE 0 
        END,
    @countSuggested=
    CASE WHEN optimum*100 >=q.answer 
        THEN @countSuggested+1 
        ELSE 0 
        END
FROM @report pr 
    INNER JOIN @question q 
    ON pr.intParticipantID=q.intParticipantID
WHERE pr.intReportID=1

select @countCurrent [Current],@countSuggested [Suggested]

Thanks in advance!

Answer 1

In a multiple table UPDATE, each target record can be updated at most once (regardless of how many times is it returned by the join).

However, you don’t need UPDATE here at all:

SELECT  @countCurrent =
        SUM
        (
        CASE
        WHEN acceptable >= @MinSuccessRate 
        THEN
                1
        ELSE
                0
        END
        ),
        @countSuggested =
        SUM
        (
        CASE
        WHEN optimum * 100 >= q.answer 
        THEN
                1
        ELSE
                0
        END
        )
FROM    @report pr 
JOIN    @question q 
ON      q.intParticipantID = pr.intParticipantID
WHERE   pr.intReportID = 1