如何使用mysql命令条件语句在Crystal报表中显示数据？

Question

I am having a problem displaying conditional statement on my crystal reports. I want to display those customers who has a "Paid" status but it seems that my code didn't work because it still displays all of my data from database.

        MySqlConnection conn;
        MySqlCommand cmd;
        MySqlDataAdapter adap;

        conn = new MySqlConnection("Server=localhost; Database=order&billing; " +
            "User ID=root; Password=; charset=utf8;"); conn.Open();
        cmd = conn.CreateCommand();
        cmd.CommandText = "select `order`.or_no,`order`.balance,`order`.totalprice, `order`.paid,customer.fname,customer.lname,customer.addr, customer.status, caterselected.catsel from `order` left join customer on `order`.custid=customer.custid left join caterselected on caterselected.nserveid=`order`.nserveid where `customer`.status='Paid'";

        adap = new MySqlDataAdapter();
        adap.SelectCommand = cmd;
        DataSet1 custDB = new DataSet1();
        custDB.Clear();
        adap.Fill(custDB, "cust");



        CrystalReport1 myReport = new CrystalReport1();
        myReport.SetDataSource(custDB); 
        crystalReportViewer1.ReportSource = myReport; 

And this is the output of my crystal reports

Answer 1

You are using somewhat strange filtering logic in your SQL query. This is the query.

select `order`.or_no,
       `order`.balance,
       `order`.totalprice,
       `order`.paid,
       customer.fname,
       customer.lname,
       customer.addr,
       customer.status,
       caterselected.catsel
  from `order` 
  left join customer on `order`.custid=customer.custid
  left join caterselected on caterselected.nserveid=`order`.nserveid
 where `customer`.status='Paid'

This where clause pulls selects customer rows with a paid status, and incidentally converts the left join customer clause to an inner join customer clause by putting a filter condition on the left table.

But there's nothing in your tables (that I can see) requiring a customer with Paid status to have only orders with Paid status. You haven't explained your business logic sufficiently for us to understand what it means for a Paid customer to have an Unpaid order.

What happens if you use this WHERE clause instead?

 where `order`.status='Paid'

Answer 2

myReport.SetDataSource(custDB.Tables(0));