C# LINQ to SQL中的子字符串和case语句

我正在将SQL转换为LINQ。有人能帮助我们在LINQ中实现下面的子字符串和case语句吗

SELECT p.goalcommitment, 
       g.goalmeasurement,
       CASE g.goalmeasurement 
           WHEN 'Count' THEN CAST(p.goalcommitmentnumber AS VARCHAR)
           WHEN 'Currency' THEN '$' + CAST(p.goalcommitmentcurrency AS VARCHAR)
           WHEN 'Percentage' THEN RTRIM(CAST(p.goalcommitmentpercentage AS VARCHAR)) + '%'
           ELSE p.pamwb_goalcommitment 
       END AS goalcommitment,
       SUBSTRING(p.domainname, CHARINDEX('\', p.domainname, 0) + 1, LEN(p.domainname) - CHARINDEX('\', p.domainname, 0))    
FROM Filtered_psp p
JOIN Filtered_goalsubtype g 
ON g.goalsubtypeid = p.goalsubtype

---

以下是您的sql在linq中的外观：

var query = from p in Filtered_psp
            join g in Filtered_goalsubtype on p.goalsubtype equals g.goalsubtypeid
            let slashLocation = p.domainname.IndexOf(@"\")
            select new
            {
                Field1 = p.goalcommitment,
                Field2 = g.goalmeasurement,
                Field3 = (p.goalmeasurement == "Count" ? p.goalcommitmentnumber.ToString() :
                          p.goalmeasurement == "Currency" ? "$" + p.goalcommitmentnumber.ToString() :
                          p.goalmeasurement == "Percentage" ? p.goalcommitmentnumber.ToString() + "%" : p.pamwb_goalcommitment),
                Field4 = slashLocation == -1 ? (p.domainname : p.domainname.Substring(slashLocation + 1, p.domainname.Length - slashLocation - 1)))
            };

---

索引和长度必须引用字符串中的位置。参数名称：长度这是我得到的异常。如果这是域名“Google\youtube”，我的期望值只是“youtube”还没有，我无法获得预期的域名，它将返回-1 gilad Green谢谢You@PankajErrolla-最后出现了什么问题？AliasName=p.DomainName==null？null:p.DomainName.Substring（p.DomainName.IndexOf（@“）+1，p.DomainName.Length-p.DomainName.IndexOf（@“）-1），通过这种方式，我解决了我的问题，现在面临来自两个不同表的分组的问题，我们如何做到这一点