为来自不同表的不同属性创建视图

Question

我有三张表：

product(pid,name,category,maker-cid)
purchase(buyer-ssn,seller-ssn,quantity,pid)
person(ssn,name,phone number,city)

如何创建视图以仅显示所有交易中的买方名称、卖方名称和产品名称？

Answer 1

您只需要连接表，投影出您需要的列并将其包装在视图中。例如：

CREATE VIEW "view name"
AS
SELECT 
    B.Name "Buyer Name",
    S.Name "Seller Name",
    PRD.Name "Product Name"
FROM Purchase PUR
JOIN Person B 
    ON B.ssn = PUR."buyer-ssn"
JOIN Person S 
    ON S.ssn = PUR."seller-ssn"
JOIN Product PRD 
    ON PRD.pid = PUR.pid;