[英]How to FULL OUTER JOIN multiple tables in MySQL
我需要FULL OUTER JOIN
多個表。 我知道如何從這里FULL OUTER JOIN
兩個表。 但是我有幾張表,我無法將其應用於它們。 我怎樣才能實現它?
我的SQL代碼如下:
INSERT INTO table
(
customer_id
,g01
,g02
,g03
,has_card
,activity
)
SELECT sgd.customer_id, sgd.g01,sgd.g02,sgd.g03,sc.value, a.activity
FROM s_geo_data sgd
LEFT JOIN s_category sc
ON sc.customer_id = sgd.customer_id
UNION
SELECT sgd.customer_id, sgd.g01,sgd.g02,sgd.g03,sc.value, a.activity
FROM s_geo_data sgd
RIGHT JOIN s_category sc
ON sc.customer_id = sgd.customer_id
UNION
SELECT sgd.customer_id, sgd.g01,sgd.g02,sgd.g03,sc.value, a.activity
FROM s_geo_data sgd
LEFT JOIN s_activity a
ON a.customer_id = sgd.customer_id
UNION
SELECT sgd.customer_id, sgd.g01,sgd.g02,sgd.g03,sc.value, a.activity
FROM s_geo_data sgd
RIGHT JOIN s_activity a
ON a.customer_id = sgd.customer_id
我也試過這個查詢:
INSERT INTO reportls.table
(
customer_id
,g01
,g02
,g03
,has_card
,activity
)
SELECT sgd.customer_id, sgd.g01,sgd.g02,sgd.g03,sc.value, a.activity
FROM s_geo_data sgd
LEFT JOIN s_category sc
ON sc.customer_id = sgd.customer_id
LEFT JOIN s_activity a
ON sc.customer_id = sgd.customer_id
UNION
SELECT sgd.customer_id, sgd.g01,sgd.g02,sgd.g03,sc.value, a.activity
FROM s_geo_data sgd
LEFT JOIN s_category sc
ON sc.customer_id = sgd.customer_id
RIGHT JOIN s_activity a
ON a.customer_id = sgd.customer_id
UNION
SELECT sgd.customer_id, sgd.g01,sgd.g02,sgd.g03,sc.value, a.activity
FROM s_geo_data sgd
RIGHT JOIN s_category sc
ON sc.customer_id = sgd.customer_id
LEFT JOIN s_activity a
ON a.customer_id = sgd.customer_id
最后一個查詢執行很長時間,我需要更快的查詢。
我認為要對 3 個表進行FULL OUTER JOIN
,您需要這樣做:
SELECT t1.value, t2.value, t3.value
FROM t1 LEFT JOIN t2 ON t1.value = t2.value
LEFT JOIN t3 ON t1.value = t3.value
UNION ALL
SELECT t1.value, t2.value, t3.value
FROM t2 LEFT JOIN t1 ON t1.value = t2.value
LEFT JOIN t3 ON t2.value = t3.value
WHERE t1.value IS NULL
UNION ALL
SELECT t1.value, t2.value, t3.value
FROM t3 LEFT JOIN t1 ON t1.value = t3.value
LEFT JOIN t2 ON t2.value = t3.value
WHERE t1.value IS NULL AND t2.value IS NULL
作為替代方案:
SELECT t1.value, t2.value, t3.value
FROM t1 FULL OUTER JOIN t2 ON t1.value = t2.value
FULL OUTER JOIN t3 ON t1.value = t3.value
我建議您創建一些臨時表,如t1
、 t2
和t3
來存儲查詢結果,然后在這些查詢上使用上面的查詢。
@ shA.t感謝測試中的A + <3
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