PHP＆SQL问题：当它不返回某些字段时，需要回显所有可能的结果

Question

Is there a way to change this sql statement to return results it does find? Basically right now orderprc.item_no and orderprc.cust_no do not always exist in the table. So if they don't my query does not return anything.

What I want to do when they don't exist is echo everything it does find, but just leave the rest blank. I am echoing these inside a table. Any suggestions? Let me know if you need more info.

SELECT 
    ordernumber.ord_num, 
    lineitem.item_no, 
    lineitem.item_desc_1,
    ordernumber.cus_no, 
    lineitem.unit_price, 
    cic.sman, 
    orderprc.description
FROM ordernumber JOIN lineitem
ON ordernumber.ord_num = lineitem.ord_num
JOIN cicmpy ON ordernumber.cus_no = cic.debcode
JOIN orderprc ON ordernumber.cus_no = orderprc.cust_no
WHERE ordernumber.ord_num = $multi_orders
  AND orderprc.item_no = lineitem.item_no
  AND orderprc.cust_no = ordernumber.cus_no
  AND getdate() between start_dt and end_dt

Answer 1

Yes, use an OUTER JOIN (spelled out in SQL statements as either LEFT JOIN or RIGHT JOIN ) as opposed to an INNER JOIN. When you just use the term JOIN , it defaults to an INNER JOIN.

In your example, the SQL statement would look like:

SELECT ordernumber.ord_num, lineitem.item_no, lineitem.item_desc_1,
    ordernumber.cus_no, lineitem.unit_price, cic.sman, orderprc.description
FROM ordernumber 
    JOIN lineitem ON ordernumber.ord_num = lineitem.ord_num
        JOIN cicmpy ON ordernumber.cus_no = cic.debcode
            LEFT JOIN orderprc ON ordernumber.cus_no = orderprc.cust_no
WHERE ordernumber.ord_num = $multi_orders
    AND orderprc.item_no = lineitem.item_no
    AND orderprc.cust_no = ordernumber.cus_no
    AND getdate() BETWEEN start_dt AND end_dt