sql MS SQL内部连接与子查询与CTE

Posted 2021-05-13

-- Database : AdventureWorks2014
-- Get All Product Names with ListPrice similar
-- to that of the Product 'LL Mountain Seat Assembly'


-- USING A NORMAL INNER JOIN
SELECT P1. Name
FROM   Production.Product AS P1
       JOIN Production.Product AS P2
         ON P1.ListPrice = P2.ListPrice
WHERE  P2. Name = 'LL Mountain Seat Assembly';


-- USING SIMPLE SUB QUERY
--  WHERE = (Scalar Subquery)
SELECT P.Name
FROM   Production.Product P
WHERE  P.ListPrice = (SELECT ListPrice
            FROM   Production.Product
            WHERE  Name = 'LL Mountain Seat Assembly');


--- USING CTE (COMMON TABLE EXPRESSION)
WITH LP (ListPrice)
     AS (SELECT ListPrice
         FROM   Production.Product
         WHERE  Name = 'LL Mountain Seat Assembly')
SELECT P.Name
FROM   Production.Product P
WHERE  P.ListPrice = (SELECT ListPrice
            FROM   LP);