I have a sql like below:
select catalog,queryname,count(*) from table group by catalog,queryname
Now how can I write it in linq and get the count?
thanks
var g =
from record in table
group record by new
{
record.catalog, record.queryname
} into mygroup
select new
{
catalog = key.catalog,
queryname = key.queryname
count = myGroup.Count()
};
Related
I have following sql statement:
Select
tsl.Transaction_Id,
tsl.State_Id,
MAX(tsl."Timestamp")
from TransactionStatesLog tsl
group by tsl.Transaction_Id
How this statement can be translated to LINQ? I just want to select the whole row, where Timestamp is maximum of the group.
With this code i am able just to select TransactionId and max Timestamp from the group.
var states = (from logs in _context.TransactionStatesLog
group logs by new { logs.TransactionId } into g
select new
{
TransactionId = g.Key,
Timestamp = g.Max(x => x.Timestamp)
}).ToList();
I am working with ef core 3.1
Assuming you forgot to add tsl.State_Id to your SQL as grouping key as follows(otherwise that SQL does not work either):
Select
tsl.Transaction_Id,
tsl.State_Id,
MAX(tsl."Timestamp")
from TransactionStatesLog tsl
group by tsl.Transaction_Id, tsl.State_Id
If I understood you correctly you need to add StateId to grouping statement as well so that you will be able to select StateId and TransactionId.
So this should work:
var states = (from logs in _context.TransactionStatesLog
group logs by new { logs.TransactionId, logs.StateId } into g
select new
{
TransactionId = g.Key.TransactionId,
StateId = g.Key.StateId,
Timestamp = g.Max(x => x.Timestamp)
}).ToList();
See: Group by with multiple columns using lambda
I want to make this query in linq to sql .
Please help. I am new to linq and having problem to with the group by clause .
Here is the sql query
select count(USERID), d.DEPTNAME from USERS u
join department d on u.DEPTID = d.DEPTID
group by u.DEPTID, d.DEPTNAME
A more direct translation would be like this:
var query =
from u in db.Users
join d in db.Departments on u.DeptId equals d.DeptId
group d by new { d.DeptId, d.DeptName } into g
select new
{
g.Key.DeptName,
Count = g.Count(),
};
Though I think it would be better off written like this:
// looks like we're counting users in each department
var query =
from d in db.Departments
select new
{
d.DeptName,
Count = db.Users.Count(u => u.DeptId == d.DeptId),
};
In linq i am trying to do like this
select * from tbl1 join tbl2 on tbl1.column1= tbl2.column1 and tbl1.column2 = tbl2.column2
how can i write the above query in Linq.... i tried like this but giving error
var sasi = from table1 in dtFetch.AsEnumerable()
join table2 in dssap.AsEnumerable()
on new {
table1.Field<string >["SAPQuotationNo"],
table1.Field<string >["Invoiceno"]}
equals new {
table2.Field<string>["SAPQuotationNo"],
table2.Field <string>["Invoiceno"]
}
Use anonymous types
give the properties names
select something
use DataRow.Field as method with round brackets
var sasi = from table1 in dtFetch.AsEnumerable()
join table2 in dssap.AsEnumerable()
on new
{
SAPQuotationNo = table1.Field<string>("SAPQuotationN"),
Invoiceno = table1.Field<string>("Invoiceno")
} equals new
{
SAPQuotationNo = table2.Field<string>("SAPQuotationNo"),
Invoiceno = table2.Field<string>("Invoiceno")
}
select table1;
You can try something like this:
from A in context.A
join B in context.B on new { id = B.ID,//..., type = A.ID,//...}
This is the hint, you can explore.
How to translate query like "select 1, 2" (i.e. without FROM clause) to LINQ statement?
Thanks!
I need to get permissions for a set of user groups. In SQL it looks like
SELECT *
FROM Permission p
INNER JOIN (SELECT GroupID
FROM [Group]
UNION ALL
SELECT 555) AS g
ON (g.GroupID = p.GroupID)
In my case I need to programmatically add a certain code instead "555". I wouldn't like to write special SQL function for that.
I guess you just want to create an anonymous type
var anonymous = new { Column1 = 1, Column2 = 2 };
Edit - Based on Comments
Depending on what your Select projection is you could do something simple like this:
If it is a Int:
var query = (from per in context.permissions
select per).AsEnumerable()
.Concat( new int[] { 1, 2 });
If it is a 'Class'
var query = (from per in context.permissions
select per).AsEnumerable()
.Concat(new CustomClass[]
{
new CustomClass()
{
Prop1= 1
},
}
);
You could also change .Concat to .Union
Why do you need this to be linq?
var numbers = new int[] { 1, 2 };
I suppose
var numbers = Enumerable.Range(1,2);
How can I write a linq to entities query that includes a having clause?
For example:
SELECT State.Name, Count(*) FROM State
INNER JOIN StateOwner ON State.StateID = StateOwner.StateID
GROUP BY State.StateID
HAVING Count(*) > 1
Any reason not to just use a where clause on the result?
var query = from state in states
join stateowner in stateowners
on state.stateid equals stateowner.stateid
group state.Name by state.stateid into grouped
where grouped.Count() > 1
select new { Name = grouped.Key, grouped.Count() };
I believe you can use a GroupBy followed by a Where clause and it will translate it as a Having. Not entirely sure though.
If you want to compare a variable that is not in the group by (Ex: age), then it would be:
var duplicated = (
from q1 in db.table1
where (q1.age >= 10 )
group q1 by new { q1.firstName, q1.lastName } into grp
where (grp.Count() > 1 )
select new
{
firstName= grp.Key.firstName,
lastName = grp.Key.lastName,
}
);