SQL连接查询帮助

目前，我有两个问题：

SELECT dateadd(month, x.MonthOffset,0) as [Month], SUM(x.itemcount) as [Total] FROM ( SELECT datediff(month,0, cna.impdate) as MonthOffset, count(*) as itemcount FROM myTable WHERE (emergency = 'Emergency') AND (impdate BETWEEN '" + fromDate + "' AND '" + toDate + "') GROUP BY impdate ) x GROUP BY MonthOffset ORDER BY MonthOffset asc SELECT dateadd(month, x.MonthOffset,0) as [Month], SUM(x.itemcount) as [Total] FROM ( SELECT datediff(month,0, cna.impdate) as MonthOffset, count(*) as itemcount FROM myTable WHERE (impdate BETWEEN '" + fromDate + "' AND '" + toDate + "') GROUP BY impdate ) x GROUP BY MonthOffset ORDER BY MonthOffset asc 这将返回2列数据和每月的项目计数

我的问题发生在一个月没有紧急物品的时候。因为我将对象传递给第二个查询，如果从第一个查询检索到的列数与第二个查询不匹配，我将收到一个索引越界错误

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我如何将我的两个查询连接在一起，这样我就可以有3列-月、紧急总数和项目总数？紧急总数可以是0或null。

我没有办法测试它，但我认为这应该能提供您想要的：

SELECT dateadd(month, datediff(month,0, cna.impdate),0) as [Month], 
       count(*) as itemcount, 
       SUM(CASE WHEN emergency = 'Emergency' THEN 1 ELSE 0 END) AS EmergencyCount
FROM myTable
WHERE impdate BETWEEN '" + fromDate + "' AND '" + toDate + "'
GROUP BY dateadd(month, datediff(month,0, cna.impdate),0)
ORDER BY [Month] asc

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我没有办法测试它，但我认为这应该能满足您的需求：

SELECT dateadd(month, datediff(month,0, cna.impdate),0) as [Month], 
       count(*) as itemcount, 
       SUM(CASE WHEN emergency = 'Emergency' THEN 1 ELSE 0 END) AS EmergencyCount
FROM myTable
WHERE impdate BETWEEN '" + fromDate + "' AND '" + toDate + "'
GROUP BY dateadd(month, datediff(month,0, cna.impdate),0)
ORDER BY [Month] asc

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很好的提议是，它将每个月的计数和紧急情况数量都放在一行中。对yookd来说，做任何他需要的事情都应该很简单…我不知道这个案例的表达方式。谢谢，它简单而优雅。很好的报价，它把计数和紧急情况的数量都放在一行中。对yookd来说，做任何他需要的事情都应该很简单…我不知道这个案例的表达方式。谢谢，它既简单又优雅。