使用C#从SQL到LINQ [英] SQL to LINQ using C#

问题描述

我正在尝试将下面的sql语句转换为linq.但是如何在我的SQL查询中获取ISNULL()区域?

Hi,

I''m trying to convert the below sql statement to linq. But how do i get the ISNULL() area in my SQL query?

SELECT DISTINCT lkpChecks.txtChecksName AS [Check Name],
    lkpChecks.intTimeInterval AS [Time Interval],
    lkpChecks.intBatchInterval AS [Batch Interval],
    lkpChecks.ynStartUp AS [Start Up],
    lkpChecks.ynCCP AS [CCP],
    lkpChecks.ynBoolean AS [Type Ok/Not Ok],
    lkpChecks.txtUnit AS [Unit],
    ISNULL(tblChecks.dblMinValue, ISNULL(lkpChecks.dblDefaultMinValue, 0)) AS [Minimum Value],
    ISNULL(tblChecks.dblMaxValue, ISNULL(lkpChecks.dblDefaultMaxValue, 0)) AS [Maximum Value],
    ISNULL(tblChecks.dblLowerWarningLimit, ISNULL(lkpChecks.dblDefaultMinWarningValue, 0)) AS [Lower Warning Value],
    ISNULL(tblChecks.dblUpperWarningLimit, ISNULL(lkpChecks.dblDefaultMaxWarningValue, 0)) AS [Upper Warning Value],
    ISNULL(tblChecks.dblTarget, ISNULL(lkpChecks.dblDefaultTargetValue, 0)) AS [Target],
    lkpChecks.ynEndFillingCode AS [Get at End of LotCode],
    lkpChecks.ynFRReport_Other AS [Include in Release Report],
    lkpChecks.intChecks,
    lkpChecks.intUserEvent,
    ynReqRemarks as [Required Remarks]
FROM lkpChecks LEFT OUTER JOIN tblChecks ON lkpChecks.intChecks = tblChecks.intChecks 
	AND tblChecks.intProcess = lkpChecks.intProcess
	AND tblChecks.intLine = 167
WHERE (lkpChecks.intProcess = 10)

var qs = from check in checksColl
	join check_sett in checkSetting
        on new
        {
            cID = check.ChecksID,
            cProcess = check.Process
        }
        equals
        new
        {
            cID = check_sett.CheckID,
            cProcess = check_sett.ProcessID
        } into temp
          from x in temp.Where(line => line.LineID == 10).DefaultIfEmpty()
where check.Process == int.Parse(c_cboProcess.Items[c_cboProcess.SelectedIndex].Key)
select new { CheckName = check.ChecksName, 
		TimeInterval = check.TimeInterval, 
		BatchInterval = check.BatchInterval, 
		Unit = check.Unit 
	   };

上面的linq是可以的，但是当我从"x"添加一些字段时，我会收到此错误对象未设置为对象的实例".

The above linq is ok, but when i add some fields from "x" i''m getting this error "Object is not set to an instance of an object".

select new { CheckName = check.ChecksName, 
		TimeInterval = check.TimeInterval, 
		BatchInterval = check.BatchInterval, 
		Unit = check.Unit,
		MinimumValue = x.MinValue,
		MaximumValue = x.MaxValue	   };

感谢您的帮助.

谢谢!!

Appreciate your help.

Thanks!!

推荐答案

添加代码以在x为null时进行更改?这就是SQL的工作.

Add code to change if x is null ? That''s what the SQL is doing.

克里斯蒂安，

感谢您的投入.

如何修复对象未设置为对象的实例" 错误消息?

我无法从"x"中获取值.

谢谢

Hi Christian,

Thanks for your inputs.

How do i fix the "Object is not set to an instance of an object" error message?

I cannot get the value from the "x".

Thanks

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