@DataSetExistCount=SELECT COUNT(*) from tblDataSet where DataSetID=@DataSet
if @DataSetExistCount== then
     @errCount = @errCount + 1
else
   >>> MORE LOGIC <<<
END

If Exists ( select 1 from tblDataSet where DataSetID = @dataSet )
begin
   -- Do your move logic
end
else
begin
    -- Doesn't exist so do something else
end