You can do something like below:
foreach(var row in dt.Rows){
string id = row["id"];
string app1 = row["Approved1"];
string app2 = row["Approved2"];
string app3 = row["Approved3"];
if(string.IsNullOrEmpty(app1) || string.IsNullOrEmpty(app2) || string.IsNullOrEmpty(app3))
return;
if(app1.ToLower()=="yes" && app2.ToLower()=="yes" && app3.ToLower()=="yes")
YesFunction();
else
NoFunction();
}
Haven't tested the code.. so, you might have to make some changes... Hope this helps..