mysql - MySQL - 从多个表中选择第一个 3rd、第二个 3rd 和第三个 3rd

Question

给定 table1、table2 和 table3（假设它们的结构相同），是否可以选择 table1、table2 和 table3 的前 1/3 记录？那么第二个1/3呢？那么最后的1/3呢？

Answer 1

第一个 1/3 记录：

SELECT *
FROM
(
    SELECT *
    FROM
    (
       SELECT * FROM Table1 
       UNION ALL 
       SELECT * FROM Table2
       UNION ALL
       SELECT * FROM Table3 
       UNION ALL
    ) sub
    ORDER BY ID DESC
    LIMIT 3
) t 
ORDER BY Id ASC
LIMIT 1

第二个2/3::

SELECT *
FROM
(
    SELECT *
    FROM
    (
       SELECT * FROM Table1 
       UNION ALL 
       SELECT * FROM Table2
       UNION ALL
       SELECT * FROM Table3 
       UNION ALL
    ) sub
    ORDER BY ID DESC
    LIMIT 3
) t 
ORDER BY Id ASC
LIMIT 2, 1

最后 1/3 记录：

SELECT *
FROM
(
    SELECT *
    FROM
    (
       SELECT * FROM Table1 
       UNION ALL 
       SELECT * FROM Table2
       UNION ALL
       SELECT * FROM Table3 
       UNION ALL
    ) sub
    ORDER BY ID DESC
    LIMIT 3
) t 
ORDER BY Id DESC
LIMIT 1

Answer 2

尝试使用 LIMIT 和 OFFSET 子句，例如：

SELECT column FROM table1 LIMIT X OFFSET Y
union
SELECT column FROM table2 LIMIT X OFFSET Y+10
union
SELECT column FROM table3 LIMIT X OFFSET Y+20

但你必须参数化 LIMIT 和 OFFSET .. 这是一种方式