Question

我有一个来自sql的查询，但我似乎无法使它在linq中工作这里是来自sql server的查询：

SELECT     MembersBU.MemberID, MembersBU.MemberFirst, MembersBU.MemberLast,
           MembersBU.MemberEmail, MembersBU.ValidEmail, 
                  MembersBU.EmailCap
FROM         groupMembers INNER JOIN
                  MembersBU ON groupMembers.MemID = MembersBU.MemberID
WHERE     (groupMembers.groupID = 3) AND (MembersBU.EmailCap = 1)

这是linq查询：

 var query = from M in MembersBUs
 join GM in GroupMembers on M.MemberID equals GM.MemID
 where (GM.GroupID = 3) & (M.EmailCap = 1)
 select new {M.MemberID, M.MemberFirst, M.MemberLast, 
             M.MemberEmail, M.ValidEmail, M.EmailCap};

感谢任何帮助。

Answer 1

你不能使用sql style where子句！您必须使用语言风格。看起来像c＃ - 你需要使用==代替：

 var query = from M in MembersBUs
 join GM in GroupMembers on M.MemberID equals GM.MemID
 where (GM.GroupID == 3) && (M.EmailCap == 1)
 select new {M.MemberID, M.MemberFirst, M.MemberLast, 
             M.MemberEmail, M.ValidEmail, M.EmailCap};

和＆amp;＆amp;而不是＆amp;。

使用此查询可能更容易 - 因为它不是匿名类型：

IQueryable<MembersBU> = from M in MembersBUs 
     where (M.GroupMember.GroupID == 3) && (M.EmailCap == 1) 
     select M;

Answer 2

您只需使用&&代替&和==代替=。否则，你的Linq查询对我来说似乎没问题......

Answer 3

var query = from M in MembersBUs 
join GM in GroupMembers on M.MemberID equals GM.MemID 
where (GM.GroupID == 3) && (M.EmailCap == 1) 
select new {M.MemberID, M.MemberFirst, M.MemberLast,  
         M.MemberEmail, M.ValidEmail, M.EmailCap};

where子句使用普通的C＃语法，==用于等式和＆amp;＆amp;逻辑AND

此外，如果您为表设置了正确的外键关系，则不需要对连接进行explcited状态。 Linq会自动推断它：

var query = from M in MembersBUs 
where (M.GroupMember.GroupID == 3) && (M.EmailCap == 1) 
select new {M.MemberID, M.MemberFirst, M.MemberLast,  
         M.MemberEmail, M.ValidEmail, M.EmailCap};

使用连接在Linq中查询

3 个答案: