NULL vs Empty String for Literal Inputs

[data-usr]

How do I use a Literal Input, and specifically set to NULL vs an empty string.

[andyvidan]

Let's assume we define a Literal Input for customer as follows:

This will allow us to use {{customer}} as a parameter in our queries.

We can now write a query as:
EXEC dbo.Test_sp @Param1 = {{customer}}

This will translate to:
EXEC dbo.Test_sp @Param1 = '<user defined value>'

So, for example, on the View page of the QueryView, you will see this input field:

If you put in foo, your query will be set to:
EXEC dbo.Test_sp @Param1 = 'foo'

If you leave the input blank, your query will be set to:
EXEC dbo.Test_sp @Param1 = ''

Now, in some cases, you may want to have NULL rather than an empty string. For that, use as the default value in the Literal Input settings.

In this case, if the user-defined value is left blank, the query will be set as:
EXEC dbo.Test_sp @Param1 = NULL