c# linq 查询在将 "StartsWith" 转换为 sql "LIKE" 时生成 "ESCAPE '~'" 语法

Question

奥拉。我在下面有这个 linq 语法，它在下面生成 sql。接收查询的 sql server 数据库拒绝 linq 附加的“ESCAPE '~'”。我仍在研究，但欢迎任何观点！

var rc = (
    from x in dc.Candidate
    join xs in dc.CandidateStatus on x.StatusId equals xs.CandidateStatusId
    join xss in dc.CandidateStatus on xs.SystemStatusId equals xss.CandidateStatusId
    where
        _active.Contains(xss.Code)
        && (x.NickName.StartsWith(startsWith) || x.FirstName.StartsWith(startsWith))
    orderby x.NickName, x.FirstName, x.LastName
    select new ListItem {
        Id = x.CandidateId,
        Label = FormatIndividual(x.LastName,x.FirstName,x.NickName)
    });
return rc.ToList<ListItem>();

SELECT [t0].[candid] AS [Id], [t0].[lastnm] AS [lastName], [t0].[firstnm] AS [firstName], [t0].[nicknm] AS [nickName]
FROM [ats].[cand] AS [t0]
INNER JOIN [ats].[candstatus] AS [t1] ON [t0].[statusid] = ([t1].[candstatusid])
INNER JOIN [ats].[candstatus] AS [t2] ON [t1].[sysstatid] = ([t2].[candstatusid])
WHERE ([t2].[code] IN (@p0, @p1, @p2)) AND (([t0].[nicknm] LIKE @p3 ESCAPE '~') OR ([t0].[firstnm] LIKE @p4 ESCAPE '~'))
ORDER BY [t0].[nicknm], [t0].[firstnm], [t0].[lastnm]

在下面实现。不再需要 sql server 通配符（'%' - 即被转义的内容）。

        ...
        //&& (x.NickName.StartsWith(startsWith) || x.FirstName.StartsWith(startsWith))
        && (x.NickName.Substring(0,1).Equals(startsWith) || x.FirstName.Substring(0,1).Equals(startsWith))
        ...

Answer 1

http://msdn.microsoft.com/en-us/library/ms179859.aspx - 参见：C. 使用 ESCAPE 子句

~ 字符被用作@p3 中值的转义字符。