Question

Lid is an autonumber field in ms access.
Error Message: Missing (operator) in query expression ‘Lid=’

db.Search_Grid_Add(LoanInfo_dgv, "Select * From Loan_Info Where Lid=" + LoanId_cb.Text + "");

Answer 1

Maybe LoanId_cb.Text is don’t parsed as int?
Try:

int lid;
string lidText = LoanId_cb.Text.Trim();
if(int.TryParse(lidText , out lid))
{
    db.Search_Grid_Add(LoanInfo_dgv, "Select * From Loan_Info Where Lid="+lidText );
}
else
{
   MessageBox.Show(lidText + " can't be parsed as int.");
}