在Oracle中选择计算列

Question

SQL新增功能和ORACLE。尝试编写此SELECT语句以创建表视图，但是我没有将其转换为Oracle。谁能帮助我破译它，并通过使它在SQL Developer中正常工作来实现？

SELECT 
OrderItems.orderID, 
Items.itemID, 
Items.itemDescription, 
Items.itemPrice, 
OrderItems.quantity, 
OrderItems.discountPercentage,
(OrderItems.quantity*itemPrice)*(OrderItems.discountPercentage/100) AS discountPerItem, 
(OrderItems.quantity*itemPrice)-((OrderItems.quantity*itemPrice)*(OrderItems.discountPercentage/100)) AS totalOrder 
FROM Inner Join OrderItems on Items.itemID = OrderItems.itemID;

错误，我得到了AS DiscountPerItem：

  

ORA-00923：找不到期望的位置00923，00000-“ FROM的FROM关键字   找不到预期的关键字”   *原因：   *操作：第8行错误：68列

Answer 1

您正在使用旧联接，可以尝试

SELECT 
OrderItems.orderID, 
Items.itemID, 
Items.itemDescription, 
Items.itemPrice, 
OrderItems.quantity, 
OrderItems.discountPercentage,
(OrderItems.quantity*Items.itemPrice)*(OrderItems.discountPercentage/100) AS discountPerItem, 
(OrderItems.quantity*Items.itemPrice)-((OrderItems.quantity*Items.itemPrice)*(OrderItems.discountPercentage/100)) AS totalOrder 
FROM Items, OrderItems
Where Items.ItemID = OrderItems.ItemID;

但是我希望您这样做。

SELECT 
OrderItems.orderID, 
Items.itemID, 
Items.itemDescription, 
Items.itemPrice, 
OrderItems.quantity, 
OrderItems.discountPercentage,
(OrderItems.quantity*Items.itemPrice)*(OrderItems.discountPercentage/100) AS discountPerItem, 
(OrderItems.quantity*Items.itemPrice)-((OrderItems.quantity*Items.itemPrice)*(OrderItems.discountPercentage/100)) AS totalOrder 
FROM Items
Inner Join OrderItems on Items.ItemID = OrderItems.ItemsID;