1
加入我寫了2個查詢一個是子查詢子查詢和內部的SQL
SELECT DISTINCT pp.employeeid
FROM payment pp JOIN Employee e
ON e.employeeid = pp.employeeid WHERE pp.employeeid IN
(SELECT employeeid
FROM employee
WHERE branchid IN
(SELECT branchid
FROM branch
WHERE code IN
(SELECT code
FROM bank p
WHERE code = 15)));
GO
等與內部聯接查詢
select DISTINCT pp.employeeid from payment pp inner join employee e
on e.employeeid=pp.employeeid
inner join branch b on b.branchid=e.branchid
inner join bank br on br.code=b.code
where br.code=15
這裏既有查詢返回相同的數據,我想問哪一個更合適?哪一個是最好使用..
內部聯接是更可讀,並在猜測,我覺得這是更快看什麼它必須做。 – Leonidas199x
更好地使用JOIN。比較查詢計劃,可能它們是相似的,可能不是 –