如何從“ TABLE1 AND TABLE2”創建SELECT查詢

Question

我有一個PostgreSQL數據庫，只有SELECT權限。 在該數據庫中，有兩個具有相同結構（相同列）的表。

我需要在每個表中編寫幾個查詢並加入結果。

有沒有辦法編寫這樣的查詢？

SELECT
  field1,
  field2,
  field3
FROM
  table1
AND
  table2
WHERE
  condition;

從2個表中選擇。 查詢= table1或table1 + table2沒有答案，這不是我的問題。

Answer 1

UNION ALL

SELECT field1, field2, field3
FROM table1
WHERE condition
UNION ALL
SELECT field1, field2, field3
FROM table2
WHERE condition;

或簡化您的WHERE條件

SELECT * FROM
(   SELECT field1, field2, field3
    FROM table1
    UNION ALL
    SELECT field1, field2, field3
    FROM table2
)
WHERE condition;

Answer 2

您可以使用聯合：

SELECT
  field1,
  field2,
  field3
FROM
  table1

UNION

SELECT
  field1,
  field2,
  field3
FROM
  table2

Answer 3

SELECT * FROM
(   SELECT field1, field2, field3
    FROM table1
    UNION ALL
    SELECT field1, field2, field3
    FROM table2
)
WHERE condition;