title: SQLite database query with multiple WHERE conditions
body: <p>Trying to develop a Windows 8.1 Store App.  Amongst other difficulties, I need to retrieve records from a sqlite database with two parameters on the where clause.  I can successfully query with one parameter in the where clause but it crashes everything when I try to use two parameters.  Here is my code for this:</p>
  
  <pre><code>    public string SaveMaint(MaintViewModel Maintenance)
      {
          string result = string.Empty;
          using (var db = new SQLite.SQLiteConnection(App.DBPath))
          {
              string change = string.Empty;
              try
              {
                  var existingmaintenance = db.Query&lt;maintenance&gt; ("select * from maintenance where VehID = ? AND MaintID = ?", new String[] {Maintenance.Maintid, Maintenance.Vehicleid});
                 // var existingmaintenance = (db.Table&lt;maintenance&gt;().Where 
                 //     (c =&gt; c.MaintID == Maintenance.Maintid).SingleOrDefault());
  
                  if (existingmaintenance != null)
                  {
                      existingmaintenance.VehID = Maintenance.Vehicleid;
                      existingmaintenance.MaintID = Maintenance.Maintid; 
                      existingmaintenance.ServiceDate = Maintenance.Servicedate;
                      existingmaintenance.ServiceCost = Maintenance.Servicecost;
                      existingmaintenance.ServiceLocation = Maintenance.Servicelocation;
                      existingmaintenance.ServiceNote = Maintenance.Servicenote;
                      existingmaintenance.ServiceOdom = Maintenance.Serviceodom;
                      int success = db.Update(existingmaintenance);
                  }
                  else
                  {
                      int success = db.Insert(new maintenance()
                      {
                          VehID = Maintenance.Vehicleid,
                          MaintID = Maintenance.Maintid,
                          ServiceDate = Maintenance.Servicedate,
                          ServiceCost = Maintenance.Servicecost,
                          ServiceLocation = Maintenance.Servicelocation,
                          ServiceNote = Maintenance.Servicenote,
                          ServiceOdom = Maintenance.Serviceodom
                      });
                  }
                  result = "Success";
              }
              catch
              {
                  result = "This project was not saved.";
              }
          }
          return result;
      }
  </code></pre>
  
  <p>Please refer to the line in which <code>existingmaintenance</code> variable is defined.  The commented out version of this line works fine.  When I substitute the variable definition with the two parameter query (obtained using a different method because I couldn't figure out how to add a second parameter to the Table query approach), it crashes.</p>
  
  <p>Thanks for any help you can give.  Sorry that I only half understand what I'm doing. </p>