i'm starter in linq, i have write this T-SQL Query
select * from DOCUMENT_TYPES where document_id in(
select document_id from Clearance_Document where Clearance_id=(select clearance_id from clearance_id from request where request_id=3))
i want convert this T-SQL Query to linq, please help me, thanks
Well, I would start first by refactoring your SQL into something other than a chain of nested sub-queries. I think this ought to do the same thing, and it's much more readable:
SELECT
*
FROM
DOCUMENT_TYPES dt
JOIN
Clearance_Document cd
ON
dt.document_id = cd.document_id
JOIN
Request r
ON
cd.clearance_id = r.clearance_id
WHERE
r.request_id = 3
(I'm assuming that from clearance_id from request was a typo.)
Then you can easily refactor into a LINQ statement:
var result = from dt in DOCUMENT_TYPES
join cd in Clearance_Document on dt.document_id equals cd.document_id
join r in Request on cd.clearance_id equals r.clearance_id
where r.request_id = 3
select new {
property1 = dt.something,
property2 = cd.somethingElse,
...
};
var result =
from a in DOCUMENT_TYPES
let list =
(
from b in Clearance_Document
where b.Clearance_id == (from c in clearance_id where request_id == 3).First<string>())
select b
).ToList()
where list.Contains(a.document_id)
select a;
Something like that should do (i guessed you're using EF, but you can easyly adapt to other LinQ-Types):
context.Document_Types.Where(doc =>
conext.Clearance_Document.Where(cd =>
cd.Clearance_Id == context.Request.Single(r => r.Request_Id == 3)
).Contains(doc.Document_Id)
).ToList();
How about
var result = c.Id context.Request.Single(r => r.Id == 3)
.Clearances.SelectMany(c => x.DocumentTypes);
In effect, get the one and only Request with an Id equal to 3, then get all the DocumentTypes of all its Clearances.
If your database is set up with the appropriate foreign keys these relationships will be automatically generated as part of your model.
Related
How can I construct the below sql query in linq query to get the results ?
SELECT PageNumber from LMS_SurveyQuestion WHERE SurveyQuestionID IN
(SELECT SurveyQuestionID from LMS_SurveyQuestionOptionChoice
WHERE NextPageNumber = 4) and SurveyID = 1
Have a look at this article. Basically, if you want to implement SQL IN query in LINQ, you need to construct an inner query first, and then use the Contains() method. Here's my attempt:
var innerQuery = (from log in LMS_SurveyQuestionOptionChoice where log.NextPageNumber = 4 select log.SurveyQuestionID);
var result = (from f in LMS_SurveyQuestion where innerQuery.Contains(f.SurveyQuestionID) && f.SurveyID = 1 select f);
Hope this will help.
try this
var result = from l in LMS_SurveyQuestion
let lsq = from l_S in LMS_SurveyQuestionOptionChoice
where l_S.NextPageNumber = 4
select l_S.SurveyQuestionID
where lsq.Contains(l.SurveyQuestionID) and l.surveyid = 1
select l.PageNumber;
I have been trying to convert this SQL statement into a linq as i am trying to move the functionality into a program.
Here is the SQL statement
SELECT cust.sg_group_name AS customer,
(SELECT Sum(du.used_space)
FROM sg_groups AS clnt
LEFT JOIN client_disk_usage AS du
ON clnt.sg_group_id = du.sg_group_id
AND clnt.group_role_id = 3
WHERE clnt.parent_group_id = cust.sg_group_id
AND du.day_of_month = 15
AND du.month_of_year = 05
AND du.used_space_year = 2016) AS disk_usage
FROM sg_groups AS cust
WHERE cust.group_role_id = 2
ORDER BY cust.sg_group_name
Essentially the output is just a list with two columns
customer disk_usage
Customer1 136401537652
Customer2 42208008210
If possible i just want to convert this to a linq statement. I have tried putting the query into LinqPad, but it doesn't seem to want to convert from SQL to Linq (just comes up with a blank white page). I have had a crack at the query myself, but i either get something that doesn't work altogether, or an incorrect number of results.
If anyone has any suggestions that would be great!
disk_usage(Sub Query) is a bit Complicated Part. Converted over here. Try this out
var CoreList = (from clnt in EntityName.sg_groups
join du in EntityName.client_disk_usage
on new { GrpId = clnt.sg_group_id, RoleId = clnt.group_role_id } equals new { GrpId = du.sg_group_id, RoleId = 3 } into LJ
from RT in LJ.DefaultIfEmpty()
where du.day_of_month == 15 && du.month_of_year == 05 && du.used_space_year == 2016
select new {clnt, du, RT}
).ToList();
var CoreListSet = CoreList.Select(i=> new YourEntityClass
{
//Fetch the ParentGroupId & UsedSpace
}).ToList();
var CoreListComplete = (from cl in CoreListSet
join cust in EntityName.sg_groups
on cust.sg_group_id equals cl.parent_group_id).ToList();
Now get the sum of CoreListComplete & just implement the base Select Query in Linq!
Apologies for the delayed response. I've marked #Anil answer up as this is the one that helped me find the answer. You solution did work #Sathish but it can be accomplished in a single command. Here is my final solution. Many thanks for your help!
storeGridUsage = (
from cust in db.sg_groups
from client in db.sg_groups
join du in db.client_disk_usage on client.SG_GROUP_ID equals du.SG_GROUP_ID
where client.GROUP_ROLE_ID == 3
where client.PARENT_GROUP_ID == cust.SG_GROUP_ID && du.DAY_OF_MONTH == day && du.MONTH_OF_YEAR == month && du.USED_SPACE_YEAR == year
where cust.GROUP_ROLE_ID == 2
orderby cust.SG_GROUP_NAME
group new {cust, du} by cust.SG_GROUP_NAME
into g
select new StoreGridUsage
{
CustomerName = g.Key,
DiskUsageInBytes = g.Sum(o => o.du.USED_SPACE)
}).ToList();
Can someone please help me convert this query to LINQ as I am new to using Linq which will then be used for google chart information.
Select Question.SubSectionName, SUM(Answers.RatingAnswer) AS Ratings
FROM Question,Answers,Response,Section
Where Answers.QuestionID = Question.QuestionID
AND Answers.ResponseID = Response.ResponseID
AND Question.SectionID=Section.SectionID
AND Section.SectionID = 2
AND Response.ResponseID = #0
AND Question.SubSectionName IS NOT Null
GROUP BY Question.SubSectionName;
What I've got so far :
var submitted = (from ans in db.Answers join ques in db.Questions on
ans.QuestionID equals ques.QuestionID
join resp in db.Responses on ans.ResponseID equals resp.ResponseID
join sec in db.Sections on ques.SectionID equals sec.SectionID
where sec.SectionID == 2 && resp.ResponseID == model.ResponseID
&& ques.SubSectionName!= null
select ques.SubSectionName && ans.RatingAnswer)
Thanks for any help.
Building on your comment this should output a grouping of sums of RatingAnswers:
var submitted =
(from ans in db.Answers
join ques in db.Questions on ans.QuestionId equals ques.QuestionId
join resp in db.Responses on ans.ResponseId equals resp.ResponseId
join sec in db.Sections on ques.SectionId equals sec.SectionId
where sec.SectionId == 2 && resp.ResponseId == model.ResponseID && ques.SubSectionName != null
select new { SubSectionName = ques.SubSectionName, RatingAnswer = ans.RatingAnswer })
.GroupBy(a => a.SubSectionName)
.Select(a => new { SectionName = a.Key, Sum = a.Sum(s => s.RatingAnswer) });
There may be a more efficient way of writing this.
I would also point out that to me the data structure seems flawed. That is, it seems either normalized incompletely or improperly. That's certainly for you to work out on your own.
Linqer helps you to convert SQL to LINQ.
If you want to get better in LINQ, I recommend using LINQPad. However, LINQPad can't convert from SQL to LINQ but from LINQ to SQL.
try this-
from q in Question
join a in Answers on q.QuestionID equals a.QuestionID
join r in Response on r.ResponseID equals a.ResponseID
join s in Section on s.SectionID equals q.SectionID
where s.SectionID= 2 and r.ResponseID= #0 and q.SubSectionName!=null
Group by q.SubSectionName
I'm trying to do a left join, not an inner join in a linq query. I have found answers related to using DefaultIfEmpty() however I can't seem to make it work. The following is the linq query:
from a in dc.Table1
join e in dc.Table2 on a.Table1_id equals e.Table2_id
where a.Table1_id == id
orderby a.sort descending
group e by new
{
a.Field1,
a.Field2
} into ga
select new MyObject
{
field1= ga.Key.Field1,
field2= ga.Key.Field2,
manySubObjects = (from g in ga select new SubObject{
fielda= g.fielda,
fieldb= g.fieldb
}).ToList()
}).ToList();
The query only gives me the rows from table 1 that have a corresponding record in table 2. I would like every record in table 1 populated into MyObject and a list of 0-n corresponding records listed in manySubObjects for each MyObject.
UPDATE:
I tried the answer to the question that is a "possible duplicate", mentioned below. I now have the following code that does give me one record for each item in Table1 even if there is no Table2 record.
from a in dc.Table1
join e in dc.Table2 on a.Table1_id equals e.Table2_id into j1
from j2 in j1.DefaultIfEmpty()
where a.Table1_id == id
orderby a.sort descending
group j2 by new
{
a.Field1,
a.Field2
} into ga
select new MyObject
{
field1= ga.Key.Field1,
field2= ga.Key.Field2,
manySubObjects = (from g in ga select new SubObject{
fielda= g.fielda,
fieldb= g.fieldb
}).ToList()
}).ToList();
However, with this code, when there is no record in table2 I get "manySubObject" as a list with one "SubObject" in it with all null values for the properties of "SubObject". What I really want is "manySubObjects" to be null if there is no values in table2.
In reply to your update, to create the null listing, you can do a ternary in your assignment of manySubObjects.
select new MyObject
{
field1= ga.Key.Field1,
field2= ga.Key.Field2,
manySubObjects =
(from g in ga select g).FirstOrDefaut() == null ? null :
(from g in ga select new SubObject {
fielda= g.fielda,
fieldb= g.fieldb
}).ToList()
}).ToList();
Here is a dotnetfiddle that tries to do what you're attempting. https://dotnetfiddle.net/kGJVjE
Here is a subsequent dotnetfiddle based on your comments. https://dotnetfiddle.net/h2xd9O
In reply to your comments, the above works with Linq to Objects but NOT with Linq to SQL. Linq to SQL will complain that it, "Could not translate expression ... into SQL and could not treat as a local expression." That's because Linq cannot translate the custom new SubObject constructor into SQL. To do that, you have to write more code to support translation into SQL. See Custom Method in LINQ to SQL query and this article.
I think we've sufficiently answered your original question about left joins. Consider asking a new question about using custom methods/constructors in Linq to SQL queries.
I think the desired Result that you want can be given by using GroupJoin()
The code Below will produce a structure like so
Field1, Field2, List < SubObject > null if empty
Sample code
var query = dc.Table1.Where(x => Table1_id == id).OrderBy(x => x.sort)
.GroupJoin(dc.Table2, (table1 => table1.Table1_id), (table2 => table2.Table2_id),
(table1, table2) => new MyObject
{
field1 = table1.Field1,
field2 = table1.Field2,
manySubObjects = (table2.Count() > 0)
? (from t in table2 select new SubObject { fielda = t.fielda, fieldb = t.fieldb}).ToList()
: null
}).ToList();
Dotnetfiddle link
UPDATE
From your comment I saw this
ga.Select(g = > new SubObject(){fielda = g.fielda, fieldb = g.fieldb})
I think it should be (depends on how "ga" is built)
ga.Select(g => new SubObject {fielda = g.fielda, fieldb = g.fieldb})
Please update your question with the whole query, it will help solve the issue.
** UPDATE BIS **
sentEmails = //ga.Count() < 1 ? null :
//(from g in ga select g).FirstOrDefault() == null ? null :
(from g in ga select new Email{
email_to = g.email_to,
email_from = g.email_from,
email_cc = g.email_cc,
email_bcc = g.email_bcc,
email_subject = g.email_subject,
email_body = g.email_body }).ToList()
Should be:
sentEmails = //ga.Count() < 1 ? null :
((from g in ga select g).FirstOrDefault() == null) ? null :
(from g in ga select new Email{
email_to = g.email_to,
email_from = g.email_from,
email_cc = g.email_cc,
email_bcc = g.email_bcc,
email_subject = g.email_subject,
email_body = g.email_body }).ToList()
Checks if the group has a First, if it doesn't the group doesn't have any records so the Action.Name for a Time Stamp has no emails to send. If the First isn't null the loop throw the group elements and create a list of Email,
var results =
(
// Use from, from like so for the left join:
from a in dc.Table1
from e in dc.Table2
// Join condition goes here
.Where(a.Id == e.Id)
// This is for the left join
.DefaultIfEmpty()
// Non-join conditions here
where a.Id == id
// Then group
group by new
{
a.Field1,
a.Field2
}
).Select(g =>
// Sort items within groups
g.OrderBy(item => item.sortField)
// Project required data only from each item
.Select(item => new
{
item.FieldA,
item.FieldB
}))
// Bring into memory
.ToList();
Then project in-memory to your non-EF-model type.
I'm using the following query and am having trouble figuring out how to add a join into it:
var chi = Lnq.attlnks.Where(a => a.ownerid == emSysid)
.Select(c => new { sysid });
How can I join this to the "attach" table (ON attlnks.sysid = attach.sysid) and select "name" where sysid is the row id?
For joins in Linq the query expression form is typically more readable than lambda syntax - I believe this is what you are asking for:
var chi = from t in Lnq.attach
join a in Lnq.attlnks
on t.sysid equals a.sysid
where a.ownerid == emSysid
select t.name;
If there is only a single entry that should match at most, you can chain a FirstOrDefault() in this case (or other alternatives like SingleOrDefault, Single, First etc.):
var chi = (from t in Lnq.attach
join a in Lnq.attlnks
on t.sysid equals a.sysid
where a.ownerid == emSysid
select t.name).FirstOrDefault();
If I understood your problem, this should work fine:
var query = from a in attlinks
join aa in attach on a.sysid equals aa.sysid into a2
where a2.sysid == a2.ownerid
select a2.Name;