Question

I want to check if my query returns any value or not and write the remaining logic accordingly.

SqlCommand myCommand = new SqlCommand("Select * from phc.userbase where [user]='@Username' and [password]='@password'", myConnection);

I want to know this command returns null or not. I tried

myReader = myCommand.ExecuteReader();
bool rd = myReader.Read();

if rd==false

but I can’t get it working. Any ideas?

Here are my parameters:

SqlParameter myParam = new SqlParameter("@Username", SqlDbType.VarChar, 25);
myParam.Value = usr;

SqlParameter myParam2 = new SqlParameter("@password", SqlDbType.VarChar, 25);
myParam2.Value = pass;

Answer 1

It depends what you mean by null here; do you mean “no rows” ? If so:

using(var myReader = myCommand.ExecuteReader()) {
    if(myReader.Read()) {
      // at least 1 row; can now check columns
    } else {
      // no rows
    }
}

To be honest, though, you could probably change that to SELECT 1 ... and use ExecuteScalar – much less bother.

In this case, though, it is probably easier to just SELECT 1 ...rest of query... and use:

object value = myCommand.ExecuteScalar();
if(value != null) { ... got a row ...}