在mysql查询中使用LIMIT和UNION时获取总行数

Question

Query:

SELECT
    tbl_a.id as aid,
    tbl_a.name as aname,
    null location,
    .....
    .....
    from tbl_a
    .........//left join to fetch some other data
    .........//where condition
UNION ALL
    0 aid,
    null aname,
    tbl_b.location as location,
    .....
    .....
    from tbl_b
    .........//left join to fetch some other data
    .........//where condition
limit '.$recordperpage.' OFFSET '.$offset.'

此处，$recordperpage和$offset是动态的。

现在我想要取得所有不。没有限制的行。

  

EXA：
  限制行数：20
  没有限制的行数：50
  我想要取消。没有限制的行（装置50）。

那么如何实现呢？ 提前谢谢。

Answer 1

也许SQL_CALC_FOUND_ROWS适合您？ 看看这里。

How to count all records but only retrieve (LIMIT) a specific number for display?

Answer 2

此查询可以解决问题：

SELECT count(*) as count
FROM
(SELECT
    tbl_a.id as aid,
    tbl_a.name as aname,
    null location,
    .....
    .....
    from tbl_a
    .........//left join to fetch some other data
    .........//where condition
UNION ALL
    0 aid,
    null aname,
    tbl_b.location as location,
    .....
    .....
    from tbl_b
    .........//left join to fetch some other data
    .........//where condition
) union_table