How to replace out of control nested conditions within an if statement - asp.net

Question

Basically we have quite a few fields within our member search.
We have a few optimized store procedures specifically for certain searches. For example if the user only searches by email address then it would use SearchMemberEmail however if it's search by postcode only then it would use SearchMemberPostcode.
This is all to do with the execution plan in sql server am told.
So we have a LONG ass if statement that basically checks if the the other text boxes are empty. i.e.
if(!string.isnullorempty(Email.Text) && string.isnullorempty(a.Text) && string.isnullorempty(b.Text)
{
Use SearMemberByemail stored procedure
}
The if statement is horrible and hard to read is there a better way of doing this?

Answer 1

You can combine the string.IsNullOrEmpty values to get one number which you can then act on. I only did this as a crude Windows Forms program which displays the intended action in a Label, but it shows the principle:
private void button1_Click(object sender, EventArgs e)
{
int choices = ((string.IsNullOrEmpty(uEmail.Text)) ? 0 : 1) +
((string.IsNullOrEmpty(uA.Text)) ? 0 : 2) +
((string.IsNullOrEmpty(uB.Text)) ? 0 : 4);
switch (choices)
{
case 1:
// search for email
label1.Text = "Email search";
break;
case 2:
// search for A
label1.Text = "A search";
break;
case 4:
// search for B
label1.Text = "B search";
break;
case 6:
// search for A+B
label1.Text = "A+B search";
break;
default:
// general search
label1.Text = "General search";
break;
}
}
Further options would use values of 8, 16, 32...