[英]How to write the following query in LINQ
我有一个SQL查询,想将其转换为linq
SELECT CAST([Date] AS DATE),
COUNT([ID]) AS 'Amount of Systems'
FROM [DemoDB].[dbo].[Servers]
WHERE [ServerID] IN ('ServerX') AND [Type] = 'Complete'
GROUP BY CAST([Date] AS DATE)
ORDER BY CAST([Date] AS DATE)
这将返回结果如下
我尝试过的
//fromDP and toDP are the names of the Datepicker's
var query = (this.db.Servers
.Where(x => x.Date >= fromDP.SelectedDate.Value &&
x.Date <= toDP.SelectedDate.Value));
var query_Success = query.Count(p => p.Type == "Complete"
&& (p.ServerID == "ServerX"));
并且我的结果总体上为Count(例如,如果我从4月1日到4月15日进行选择,则结果为所有“完成”的总和),但是我需要在此选定范围内每天进行计数。 结果我将绑定到柱形图。 如何进行 ?
this.db.Servers.Where(s => s.ServerId == "ServerX" && s.Type == "Complete")
.GroupBy(s => s.Date)
.OrderBy(s => s.Key)
.Select(g => new { Date = g.Key, AmountOfSystems = g.Count() });
将Where子句更改为
Where(s => s.ServerId == "ServerX" && s.Type == "Complete" && s.Date >= fromDP.SelectedDate.Value && s.Date <= toDP.SelectedDate.Value)
过滤到有限的日期范围。
编辑
如@ vvs0205建议。 使用EntityFunctions类来按需操纵日期列: http : //msdn.microsoft.com/zh-cn/library/system.data.objects.entityfunctions.aspx
如果我理解正确,那么作者只想使用日期而不使用时间。 为此,我们可以使用EntityFunctions.TruncateTime
方法来修剪时间部分。 我将基于@steaks答案:
db.Servers.Where(s => s.ServerId == "ServerX" && s.Type == "Complete")
.GroupBy(s => EntityFunctions.TruncateTime(s.Date))
.OrderBy(s => s.Key)
.Select(g => new {Date = g.Key, AmountOfSystems = g.Count()});
像这样
var fromDate = fromDP.SelectedDate.Value;
var toDate= toDP.SelectedDate.Value;
var q = from server in this.db.Servers
where (server.Date >= fromDate && server.Date<=toDate && server.ServerID="ServerX" && server.Type=="Complete")
group server by server.Date
into g
orderby g.Key
select new
{
Date = g.Key,
Count = g.Count()
};
var results = q.ToList();
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