将旧连接转换为SQL92

Question

如何使用LEFT OUTER和RIGHT OUTER Join将以下查询转换为SQL 92？

SELECT in.ItemNo, ip.ItemPrice, c.CustomerName
FROM inventories in, InventoryPrice ip, Customer c
WHERE in.itemno * = ip.itemno
AND ip.CustId = * c.CustId

Answer 1

select
     in.ItemNo
    ,ip.ItemPrice
    ,c.CustomerName
from       inventories    as in
left  join InventoryPrice as ip on ip.itemno = in.itemno
right join Customer       as  c on ip.CustId = c.CustId

请注意，旧版连接代码上的反向语法会导致混淆左侧 - 然后右侧连接。这实际上似乎是遗留代码中的一个错误，但是如果不精确地了解数据结构就无法确定..

Answer 2

SELECT in.ItemNo, ip.ItemPrice, c.CustomerName
FROM inventories AS in
LEFT JOIN InventoryPrice AS ip ON ip.itemno = in.itemno
LEFT JOIN Customer AS c ON ip.CustId = c.CustId