Blank Parameter to Null Parameter in SSRS
reporting-services
Solution
If you're second report is expecting a NULL values, (i.e. `Nothing` in SSRS), you can pass an expression-based parameter to the child report based on the parent parameter, making sure that if it's an empty string at the parent level, you can explicitly set this to Nothing:
=IIf(Parameters!valid.Value = "", Nothing, Parameters!valid.Value)
This way the empty string will never get passed and your child report; only the NULL value it expects.
Problem
I have a drilldown report whose parameters are: parent report - @valid Nvarchar(20) = '' and in child report - @valid Nvarchar(20) = Null. Both reports run very well but I have an issue after mapping up this parameters in the Text Box Properties > Action > Go to Report. When the report is run I get the error, "the value provided for the report parameter is not valid" The query for this report is from a stored Procedure. In the child report, Parameter Properties, I have ticked the "allow Null values" text box, Set available parameter to come from a query and specify a default value to come from a query. What have I done wrong to allow for the error returned? Your help is appreciated. Thank you.