在SSRS数据集SQL查询中创建新行以在报告参数中使用

Question

I am going round in circles with a bit of SQL and would appreciate some help.

I've looked up creating temp tables, nested Select statements (where advice seems to be to avoid these like the plague) and various uses of Case statements but I can't seem to find a solution that works. I'd say I'm beginner level for SQL.

I have a table with 10 relevant records. The query that works to return all the relevant entries in the table is:

SELECT
     TblServAct.ServActId   
    ,TblServAct.ServActName  
FROM TblServAct 
WHERE TblServAct.ServActExclude IS NULL 
ORDER BY TblServAct.ServActName

Here is where I run into problems:

When the parameter (@YESNOActivity) = Yes, I want all the rows in the table to be returned. I have managed to do this with a CASE statement

...however when the parameter (@YESNOActivity) = No, I want ONLY ONE row to be returned which doesn't actually exist in the table (and should not be inserted into the actual table). The values that I need to insert are: ServActId = 101 and ServActName = 'Select YES in Parameter2 to filter by Service Activity'

For background, the reason I am doing this is because I have found SSRS report parameters to be especially difficult to conditionally format. I want to use the dataset above to return a message in a parameter (lets call it parameter2) that the user needs to select yes in (@YESNOActivity) in order to see the full selection list in parameter2.

If I can get this to work I can see lots of potential for re-use so all advice appreciated

Thanks Eileen

Answer 1

I believe this should do the job, just include your parameter in the WHERE clause and UNION it with your own row of data.

SELECT
     TblServAct.ServActId   
    ,TblServAct.ServActName  
FROM TblServAct 
WHERE TblServAct.ServActExclude IS NULL
  AND @YESNOActivity = 'Yes'
UNION ALL
SELECT
     ServActId = 101
    ,ServActName = 'Select YES in Parameter2 to filter by Service Activity'
WHERE @YESNOActivity = 'No'
ORDER BY TblServAct.ServActName

Answer 2

One way is to use this query:

SELECT 
  TblServAct.ServActId   
  ,TblServAct.ServActName  
FROM TblServAct 
WHERE TblServAct.ServActExclude IS NULL 
  AND 'Yes' = @YESNOActivity
UNION ALL
SELECT 
  101 AS ServActId 
  ,'Select YES in Parameter2 to filter by Service Activity' AS ServActName
WHERE 'No' = @YESNOActivity
ORDER BY TblServAct.ServActName

Another way would be to create two data flows and use your variable in a constraint to send the processing to one or the other.

A third way would be to put an expression on the SQL command and use your variable to switch between two SQL statements.