Question

我在下面有一个查询，我想要返回关键＆amp;的总数。警告一天的警报，但我遇到的问题是，当我在天数范围内进行警报时，它会添加指定日期的严重警报

SELECT alertDate as "Alert Date",
    (SELECT COUNT(alertType) FROM alerts WHERE alertDate BETWEEN '2016/02/15' AND '2016/02/16' AND UPPER(alertType)='CRITICAL') as Critical,
    (SELECT COUNT(alertType) FROM alerts WHERE alertDate BETWEEN '2016/02/15' AND '2016/02/16' AND UPPER(alertType)='WARNING') as Warning
FROM alerts
where alertDate BETWEEN '2016/02/15' AND '2016/02/16'
GROUP BY alertDate;

尝试了上面的代码，但显然我无法添加＆＃34; group by＆＃34;子查询中的子句，我认为是问题，请帮助我如何解决这个问题......

Answer 1

你可以使用sum（case）：

SELECT alertDate as "Alert Date",
    sum(case when UPPER(alertType)='CRITICAL' then 1 end) as Critical,
    sum(case when UPPER(alertType)='WARNING' then 1 end) as Warning
FROM alerts
where alertDate BETWEEN '2016/02/15' AND '2016/02/16'
GROUP BY alertDate;

Answer 2

您希望条件聚合 - case进入聚合函数。我会把它写成：

SELECT alertDate as AlertDate,
       SUM(CASE WHEN UPPER(alertType) = 'CRITICAL' THEN 1 ELSE 0 END) as Critical,
       SUM(CASE WHEN UPPER(alertType) = 'WARNING' THEN 1 ELSE 0 END) as WARNING
FROM alerts a
WHERE alertDate BETWEEN '2016-02-15' AND '2016-02-16'
GROUP BY alertDate;

如果您使用的是MySQL，可以将其缩短为：

SELECT alertDate as AlertDate,
       SUM(UPPER(alertType) = 'CRITICAL') as Critical,
       SUM(UPPER(alertType) = 'WARNING') as Warning
FROM alerts a
WHERE alertDate BETWEEN '2016-02-15' AND '2016-02-16'
GROUP BY alertDate;

请注意其他一些变化：

不需要任何子选择。
我从AlertDate删除了空格。我不喜欢需要转义的列别名。
我将/替换为日期文字中的- - 连字符与ISO 8601兼容。

Answer 3

您应该使用像

这样的条件计数

SUM( case when alertDate BETWEEN '2016/02/15' AND '2016/02/16' 
     AND UPPER(alertType)='CRITICAL' then 1 else 0 end) as Critical,

在单个查询中使用多个Count

3 个答案: