Question

我有一个sql查询，它会给我大约30条记录但同样的查询一旦我改为linq查询它给我数千条记录。我无法找到问题的实际根本原因可以帮助我...

sql查询

            select 
DLId = p.Id,
TopicId = st.Id,
TopicName = at.Name,
PrimaryOrg = bo.BusinessUnit,
StatusId = ns.ID,
ModifiedBy = pa.LastName 

from  STopics st
join ATopics at on st.Id = at.Id
join Students p on st.StudentId = p.Id
join Sorgs sbu on at.BUorgID = sbu.BUOrgID
join BOrgs bo on sbu.BUOrgID = bo.ID
join Status ns on st.SID = ns.ID
 join Students pa on st.NominatedBy = pa.Email
where p.IsActive = 1 and sbu.StudentID = 123 and sbu.IsActive = 1

和linq查询是

(from st in Context.STopics 
join at in Context.ATopics  on st.Id equals at.Id
join p in Context.Students  on st.StudentId  equals p.Id 
join sbu in Context.Sorgs  on at.BUorgID equals sbu.BUOrgID  
join bo in Context.BOrgs  on sbu.BUOrgID equals bo.ID
join ns in Context.Status  on st.SID equals ns.ID
join pa in Context.Students  on st.NominatedBy equals pa.Email
where  p.IsActive==true && sbu.StudentID == 123 && sbu.IsActive == true
 select new result()
 {
 DLId = p.Id,
  TopicId = st.Id,
  TopicName = at.Name,
 PrimaryOrg = bo.BusinessUnit,
 StatusId = ns.ID,
 ModifiedBy  = pa.LastName
 })

Answer 1

(from st in Context.STopics 
join at in Context.ATopics  on st.Id equals at.Id
join p in Context.Students  on new { st.StudentId, p.IsActive }   equals new { p.Id , true}
join sbu in Context.Sorgs  on new { sbu.BUorgID, sbu.IsActive,sbu.StudentID }  equals new { at.BUorgID , true, 123}
join bo in Context.BOrgs  on sbu.BUOrgID equals bo.ID
join ns in Context.Status  on st.SID equals ns.ID
join pa in Context.Students  on st.NominatedBy equals pa.Email
select new result()
{
DLId = p.Id,
TopicId = st.Id,
TopicName = at.Name,
PrimaryOrg = bo.BusinessUnit,
StatusId = ns.ID,
ModifiedBy  = pa.LastName
})

你能试试这个，如果你想得到确切的问题，你可以从linq语句中获得如何生成sql查询，linq查询使用了大量的内部查询方法

var query= your linqquery;
string sqlQuery=query.ToString();

you can review sqlQuery.

Linq查询比sql查询获取更多记录

1 个答案: