Question

我正在寻找一个更好的，但无法在互联网上找到它（maby，因为我不知道正确的术语）。我正在搜索对我的值进行分组的查询，并为预定义值显示零。

我的表的值为0 - 5（例如1,0,4,4,0,0,4,2,1,5,0）

我需要一个始终显示数字的查询（也是零值）：

nr |量
0 | 4
1 | 2
2 | 1
3 | 0
4 | 3
5 | 1

这可能吗？

Greets，Len

Answer 1

Here is what you need. This assumes that you know up-front that the values 0-5 are the only possible values that can be present in your table. If other values are present, that's OK but you won't count them.

ScriptsAndPrograms

SQL Fiddle here:

http://sqlfiddle.com/#!9/bc704f/12

Answer 2

Create a numbers table with single column "num" and insert all your numbers (0-5).

Then do a left join query and group by the num like this:

XmlSerializer serializer = new XmlSerializer(typeof(Incident));
using (StringReader reader = new StringReader(xmlDocumentText))
{
    Incident incident= (Incident)(serializer.Deserialize(reader));
}

mysql查询组并显示可能的值

2 个答案: