[英]Selecting Rows from one table based on conditions in two separate tables
我曾嘗試使用joins和where語句進行以下操作,但由於運行時間太長而導致超時或出現重復的列名錯誤。
我有3個表:A,B,C我想基於B和C的約束創建一個由A的行組成的表。因此A中的行必須滿足B或C中的條件:
(A.ID = B.ID和A.PURCHASE = B.PURCHASE)或(A.ID = C.ID和A.PURCHASE = C.PURCHASE)。
我一直在使用mysql大約一個星期,這是我最近得到的(掛起):
CREATE TABLE D
SELECT T1.*
FROM TABLE A AS T1, TABLE B AS T2, TABLE B AS T3
JOIN T2, T3 ON ((T1.CUSTOMER_ID = T2.CUSTOMER_ID AND T1.DAY_ID =
T2.DAY_ID) OR (T1.CUSTOMER_ID = T3.CUSTOMER_ID AND T1.DAY_ID = T2.DAY_ID));
謝謝你的幫助!
連接在一起的A,B和C使用LEFT JOIN
,然后保留從A記錄,其中一個匹配發生在B 或 C.
INSERT INTO D
SELECT DISTINCT a.* -- remove duplicate records
FROM tableA a
LEFT JOIN tableB b
ON a.CUSTOMER_ID = b.CUSTOMER_ID AND a.DAY_ID = b.DAY_ID
LEFT JOIN tableC c
ON a.CUSTOMER_ID = c.CUSTOMER_ID AND a.DAY_ID = c.DAY_ID
WHERE b.CUSTOMER_ID IS NOT NULL OR -- retain records where either
c.CUSTOMER_ID IS NOT NULL -- condition matches
如果尚未創建D表,則使用與表A相同的定義來創建它。
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