Question

我正在使用iReport创建一个JasperReport，因此，我对一个SQL查询的限制*。
我有一个'统计'表，带有'name'（VARCHAR），'count'（INTEGER）和'datetime'（DATETIME）列。
当'name'为最后一天的“test”时，很容易获得'count'列的总和，并且类似于上周和月（见下文）

工作SQL语句：


SELECT
  SUM(count)as 'today'
FROM
  statistics
WHERE
   name = "test"
  AND $P{oneDayAgo} <= datetime
  AND datetime <= $P{now}

但是，由于我只有一个SQL语句可以使用，我需要以某种方式组合它们。我尝试使用UNION（如下），但这不起作用。

SQL语句失败：

SELECT
     SUM(count)as 'today'
FROM
     statistics
WHERE
     name = "test"
 AND $P{oneDayAgo} <= datetime
 AND datetime <= $P{now}
UNION
SELECT
     SUM(count)as 'thisWeek'
FROM
     statistics
WHERE
     name = "test"
 AND $P{oneWeekAgo} <= datetime
 AND datetime <= $P{now}
UNION
SELECT
     SUM(count)as 'thisMonth'
FROM
     statistics
WHERE
     name = "test"
 AND $P{oneMonthAgo} <= datetime
 AND datetime <= $P{now}

（*）可以只为图表或交叉表添加其他查询，这些查询都不能满足我的目的。

Answer 1

总和（情况 - 条件 - 然后计数，否则0结束）

SELECT
  SUM(case when $P{oneDayAgo} <= datetime then count else 0 end) as 'today',
  SUM(case when $P{oneWeekAgo} <= datetime then count else 0 end) as 'thisweek',
  SUM(count) as 'thismonth'
FROM
  statistics
WHERE
   name = "test"
  AND $P{oneMonthAgo} <= datetime
  AND datetime <= $P{now}

请注意，如果您需要平均值，请务必将NULL替换为0。

Answer 2

UNION'd查询应生成相同的列（名称，类型）。将未使用的列设置为NULL或使用差异列：

SELECT
     SUM(count) as `total`,
     'today' as `when`
FROM
     statistics
WHERE
     name = "test"
 AND $P{oneDayAgo} <= datetime
 AND datetime <= $P{now}
UNION
SELECT
     SUM(count) as `total`,
     'thisWeek' as `when`
FROM
     statistics
WHERE
     name = "test"
 AND $P{oneWeekAgo} <= datetime
 AND datetime <= $P{now}
UNION
SELECT
     SUM(count) as `total`,
     'thisMonth' as `when`
FROM
     statistics
WHERE
     name = "test"
 AND $P{oneMonthAgo} <= datetime
 AND datetime <= $P{now}

Answer 3

您有两个选择：

1）删除每个查询的“as”部分，然后它将作为1列没有名称

2）创建临时表并将这些行插入临时表，然后查询临时表

如何在iReport中使用SQL查询同一项的多个SUM

3 个答案: