ExecuteReader, SmtpMail, Access empty cell errors

[crxcte1]

The access database has 3 cells on each line and some are empty. When a empty cell is read I get an error. How could I step over an empty cell and so not to create an error?

strSQL="Select email1, email2, email3 from members where membertype=Officers";
try {
OleDbCommand cmd = new OleDbCommand(strSQL, myConn);
myConn.Open();
drMembers = cmd.ExecuteReader();
while (drMembers.Read()) {
string sTo = drMembers["email1"].ToString();
MyMail.To = sTo.Trim();
if (sTo != "" || sTo != null)
SmtpMail.Send(MyMail);//first email sent
sTo = drMembers["email2"].ToString();
MyMail.To = sTo.Trim();
if (sTo != "")
SmtpMail.Send(MyMail);//2nd email sent
sTo = drMembers["email3"].ToString();
MyMail.To = sTo.Trim();
if (sTo != "")
SmtpMail.Send(MyMail); //3rd email sent
}
Span1.InnerHtml ="<B><font color=green>Message sent</font></B>";
myConn.Close();
}
catch (Exception ex1){
Span1.InnerHtml ="<B><font color=Yellow>Message not sent</font></B>";
}

 

[Veep]

You need to trap for string.empty or DBNull.Value before you do any kind of assignment.ToString() from the drMembers object.

while (drMembers.Read()) {
string sTo;
if(!drMembers.Equals(DBNull.Value) && !drMembers["email1"].ToString() == string.empty)
  {
     sTo = drMembers["Email1"].ToString();
     MyMail.To = sTo.Trim();
  {
etc......

Of course you're going to want to do something else if it's null or "".

 

[crxcte1]

I tried your example and got an error as listed below;

Operator '!' cannot be applied to operand of type 'string'
Source Error:

Line 172: while (drMembers.Read()) {
Line 173: string sTo;
Line 174: if(!drMembers.Equals(DBNull.Value) && !drMembers["email1"].ToString() == string.empty){
Line 175: sTo = drMembers["email1"].ToString();
Line 176: MyMail.To = sTo.Trim();

Line: 174

 

[Veep]

Sorry, I'm out of it right now and shouldn't be anywhere near a computer. I tell you not to do the .ToString() thing and then I do it in my example as part of the validation. Get rid of this whole part of the if: && !drMembers["email1"].ToString() == string.empty.
Sorry again.

 

[crxcte1]

Yes, my head always hurts when I work with this code. I tried removing the .ToString which lead to another error. I wasn't sure if that was what you were referring to.

Compiler Error Message: CS0023: Operator '!' cannot be applied to operand of type 'object'

Source Error:


Line 172: while (drMembers.Read()) {
Line 173: string sTo;
Line 174: if(!drMembers.Equals(DBNull.Value) && !drMembers["email1"] == string.empty){
Line 175: sTo = drMembers["email1"].ToString();
Line 176: MyMail.To = sTo.Trim();


Source File: C:\ASPdotnet\MembersList\MailAp.aspx Line: 174

 

[Veep]

OK. New day. Had coffee.

string sTo;
while (drMembers.Read()) {
if(!drMembers[b]["Email1"][/b].Equals(DBNull.Value))
  {
     sTo = drMembers["Email1"].ToString();
     MyMail.To = sTo.Trim();
  {
etc......