sql - 带有子查询的 Oracle sql 查询还是我应该规范化？

Question

我有以下查询有效，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 Commitment 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？

或者我应该规范化并将 4 个员工徽章拆分到一个单独的表格中？如果我要规范化，似乎我存储徽章的新表需要某种角色列，然后我是否需要第三个查找表来存储该角色？然后让事情复杂化，我需要使用传入的绑定(bind)变量“dept”通过 Approver_ID 查询 promise 。不知道该走哪条路。

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

Answer 1

采用:

   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 friend - 表设计很好。