Rdlc Distinct values for string and not a number

Question

Question reguarding the rdlc file.

How do you choose a distinct value via a string or text in the expression properties. I know how to do it for access, but how do you choose a distinct value for expression in the rdlc file.

I want to produce the output below

example:

Test          Param

black           cat
black           car
black           hat
blue            cat
blue            car
blue            hat

Output:

Test         TotalParam

black              3
blue               3