根据参数值左连接结果

In my stored procedure I am trying to get the results of a query according to parameter. I have a main table "employee" and table "employee_process" which I make left join with the first one. In the results if the parameter's value is 0 I want to get everything from "employee" except the rows which are joined with "employee_process" and if the value is 1 I want to get only the rows which are joined between the two tables. Here is what I have now:In my stored procedure I am trying to get the r