select distinct dept from T
where 1=1 ${if(or(len(user_name) == 0,user_name = “A”),””,”and COALESCE((select distinct research from m where login = '" + user_name + "'),'not exists') = dept")} and dept<>''
${if(or(len(user_name) == 0,user_name = "A"),"","and COALESCE((select distinct research from m where login = '" + user_name + "'),'not exists') = dept")} and dept<>''