非常简单的LINQ查询，将文本框值传递给where子句

Question

I want my LINQ query to count the number of instances a member is present in a table based on what the user enters into a textbox.

As a result, I have the following

protected void btnSubmit_Click(object sender, EventArgs e)
{
    LoginDataContext lg = new LoginDataContext();

    int logincheck = (from r in lg.tblOnlineReportingLogins
                      where r.MemberID == tbxMember.Text.ToString()
                      select r).Count();

When I debug this, the value appears as 0 when I know this is not the case.

Can someone point out where I am going wrong?

Answer 1

I suppose the MemberId property is an integer. So you cannot compare it against a string value. Text.ToString() is redundant anyway, since Text is already a string.

where r.MemberId.ToString() == tbxMember.Text

should work.

A cleaner solution would be to parse the Text property into an int value (together with some validity checking) and do the comparison using int s, like

int targetId;
if (Int32.TryParse(tbxMember.Text, out targetId)) {
    int logincheck = (from r in lg.tblOnlineReportingLogins
                  where r.MemberID == tbxMember.Text.ToString()
                  select r).Count();
    // ...
} else {
    MessageBox.ShowMessage("Invalid Id");
}

EDIT : Sorry, perhaps I was too quick, I assumed MemberId was an integer. But in this case, your code shouldn't even have compiled. I'm just wondering about the upvotes :-) ...