Oracle sql 查询带有子查询还是应该规范化？

Question

我有以下有效的查询，但我想知道它是否可以更有效。我需要电话簿表 (pb) 中 4 名员工的名字和姓氏，他们的徽章（员工 ID）存储在承诺表中

SELECT Originator_ID, 
(SELECT pb.lname FROM pb WHERE pb.badge = Commitment.Originator_ID) AS Originator_Last_Name, 
(SELECT pb.fname FROM pb WHERE pb.badge = Commitment.Originator_ID) AS Originator_First_Name, 
Checker_ID, 
(SELECT pb.lname FROM pb WHERE pb.badge = Commitment.Checker_ID) AS Checker_Last_Name, 
(SELECT pb.fname FROM pb WHERE pb.badge = Commitment.Checker_ID) AS Checker_First_Name, 
Reviewer_ID, 
(SELECT pb.lname FROM pb WHERE pb.badge = Commitment.Reviewer_ID) AS Reviewer_Last_Name, 
(SELECT pb.fname FROM pb WHERE pb.badge = Commitment.Reviewer_ID) AS Reviewer_First_Name, 
Approver_ID, 
(SELECT pb.lname FROM pb WHERE pb.badge = Commitment.Approver_ID) AS Approver_Last_Name, 
(SELECT pb.fname FROM pb WHERE pb.badge = Commitment.Approver_ID) AS Approver_First_Name 
FROM Commitment 
WHERE Commitment.Approver_ID IN (SELECT pb.badge FROM pb WHERE pb.dept = ?) ORDER BY Commitment_ID  

我的查询是否有太多子查询？

或者我应该标准化并将 4 个员工徽章分解到一个单独的表中？如果我要标准化，似乎我存储徽章的新表需要某种角色列，然后我是否需要该角色的第三个查找表？然后，让事情变得复杂的是，我需要使用传入的绑定变量“dept”按 Approver_ID 查询承诺。不确定该走哪条路。

TABLE: commitment_emp
Commitment_ID (PK) (FK) VARCHAR2(10)
badge (PK) VARCHAR2(10)
role (PK) VARCHAR2(20)

Answer 1

使用：

   SELECT c.originator_id, 
          orig.lname,
          orig.fname,
          c.checker_id,
          check.lname,
          check.fname,
          c.reviewer_id,
          review.lname,
          review.fname,
          c.approver_id,
          approve.lname,
          approve.fname
     FROM COMMITMENT c
LEFT JOIN PB orig ON orig.badge = c.originator_id
LEFT JOIN PB check ON check.badge = c.checker_id
LEFT JOIN PB review ON review.badge = c.reviewer_id
     JOIN PB approve ON approve.badge = c.approver_id
                    AND approve.dept ?
 ORDER BY c.commitment_id

JOIN 和表别名是你的朋友 - 表设计很好。