SQL Server中表之間的參照完整性

Question

我有2個表格， Members和Enrollments 。 可以使用主鍵Member ID來連接兩個表。

我需要編寫一個查詢，該查詢返回Members表中的所有成員，而Enrollments表中沒有相應的行，反之亦然。

這是我到目前為止的內容：

IF OBJECT_ID('tempdb..#memberswithoutenrollments') IS NOT NULL
    DROP TABLE #memberswithoutenrollments 

SELECT m.* 
INTO #memberswithoutenrollments 
FROM ABC_Members m 
LEFT OUTER JOIN ABC_MemEnrollment e ON m.MemberID = MemberID

Answer 1

FULL JOIN是比較兩個表之間的列表的一種簡單方法：

SELECT COALESCE(e.MemberID, m.MemberID),
       (CASE WHEN e.MemberID IS NULL THEN 'No Enrollments' ELSE 'No Member' END)
FROM ABC_Members m FULL JOIN
     ABC_MemEnrollment e
     ON m.MemberID = e.MemberID
WHERE e.MemberID IS NULL OR m.MemberID IS NULL;

但是，如果您具有適當的外鍵關系，那么在沒有成員的情況下永遠不要注冊。

Answer 2

您可以NOT IN這里使用NOT IN以使您受益。

WITH
    -- Create a list of all of the matches
    in_table AS
        (
            SELECT
                Member_ID
            FROM
                Enrollments
            WHERE
                Members.MemberID = Enrollments.Member_ID
        ),

    result_table AS
        (
            SELECT
                *

            FROM
                Members

            -- Grab only the values from members that DO NOT APPEAR in in_table
            WHERE
                MemberID NOT IN (SELECT DISTINCT FROM in_table)
        )

-- Grab all results
SELECT * FROM result_table