I have created some solution and worked for me:
In Expression
field, I put first expression:
1. Iif(Parameters!FilterColumn.Value = "All", 1, Fields!Category.Value)
In Value
field, I put second expression:
2. Iif(Parameters!FilterColumn.Value = "All", 1, Parameters!FilterColumn.Value)
So, when I choose "All" value in parameter, then first expression will result 1, and second expression will result 1, and i have 1 = 1
which is true for all rows, and I got all rows in table.
When I choose specific category from parameter, then in first expression result will be Fields!Category.Value
and in second expression will be Parameters!FilterColumn.Value
. Simple, I got Fields!Category.Value = Parameters!FilterColumn.Value
, or just give me rows where category is that choosen in parameter.