I would like to have a single LINQ to SQL query to count 2 entities from the same table. E.g. Count number of employees and managers from table Personnel.
Example:
var q = from p in db.Personnel
where p.PersonType == 'Manager' || p.PersonType == 'Employee'
select new
{ NoOfPersonnel = p.Count(p => p.PersonType == 'Employee'), //Wrong way
NoOfManagers = p.Count(p => p.PersonType == 'Manager') //Wrong way
}
How can I do it?
Try this:
var list = from employee in db.Personnel
where employee.PersonType == "Manager" || employee.PersonType == "Employee"
group employee by employee.PersonType
into temp
select new { PersonType = temp.Key, Count = temp.Count() };
Related
i have a linq query but in where clause is conditional. if eve.EventType is null then it will not include in where clause. How can we do with Linq lambda expression
var data= (from reg in product
join se in _order on reg.EventSessionId equals se.EventSessionId
join eve in Event on se.EventId equals eve.EventId
where eve.EventType == (EventType)eventType &&
((!string.IsNullOrEmpty(eve.EventName) && eve.EventName.Contains(SearchText, StringComparison.OrdinalIgnoreCase))
select (new OrderHistory
{
RegistrationId = reg.RegistrationId,
EventName = eve.EventName,
EventSesionName = se.EventSesionName,
})).ToList();
Thanks
This may help you.You should check null at first of your expression.
var data= (from reg in product
join se in _order on reg.EventSessionId equals se.EventSessionId
join eve in Event on se.EventId equals eve.EventId
where eve.EventType != null && eve.EventType == (EventType)eventType &&
((!string.IsNullOrEmpty(eve.EventName) && eve.EventName.Contains(SearchText, StringComparison.OrdinalIgnoreCase))
select (new OrderHistory
{
RegistrationId = reg.RegistrationId,
EventName = eve.EventName,
EventSesionName = se.EventSesionName,
})).ToList();
I have this query and i wanted to only select distinct value from Charges table(Port Name must only display once).
public List<Port> GetPortsByCountryOrigin(int countryId, TransportDirection transdirection, TransportType transtype)
{
using (var ctx = CreateDbContext())
{
return (from item in ctx.Ports
join s in ctx.Charges
on item.PortId equals s.PortId
where (s.TransportDirection == transdirection &&
s.TransportType == transtype
&& item.CountryId == countryId)
select item).ToList();
}
}
Currently, the Ports.Name are repeating values.
Try .Distinct() before your ToList()
I have written some LINQ to simulate an SQL GroupBy statement (see below). However, I also need to only consider only the last 10 settingIds before doing my group by. I think I would use Take to do this, but what would be the correct syntax in my statement?
var settings2 = from s in dc.SystemSettings
where s.campConfig.campaignType == campType
&& s.campId != campId
&& s.settingKey == ticket.setting.Key
orderby s.settingId descending
group s by s.settingValue
into grp
select new
{
SettingValue = grp.Key,
SettingCount = grp.Select(x => x.settingValue).Count()
};
I would do something like this
var settings2 = from sOuter in
(from s in dc.SystemSettings
where s.campConfig.campaignType == campType
&& s.campId != campId
&& s.settingKey == ticket.setting.Key
orderby s.settingId descending
select s).Take(10)
group sOuter by sOuter.settingValue
into grp
select new
{
SettingValue = grp.Key,
SettingCount = grp.Select(x => x.settingValue).Count()
};
How to expand this query:
public Dictionary<int, List<TasksInDeal>> FindAllCreatedTasks()
{
return (from taskInDeal in db.TasksInDeals
where taskInDeal.Date > DateTime.Now && taskInDeal.Date < DateTime.Now.AddDays(7)
group taskInDeal by taskInDeal.CreatedByUserID
into groupedDemoClasses
select groupedDemoClasses).ToDictionary(gdc => gdc.Key, gdc => gdc.ToList());
}
into something like this:
public Dictionary<int, List<TaskForNotification>> FindAllCreatedTasks()
{
return (from taskInDeal in db.TasksInDeals
join user in db.Users on taskInDeal.CreatedByUserID equals user.UserID
where taskInDeal.Date > DateTime.Now && taskInDeal.Date < DateTime.Now.AddDays(7)
group taskInDeal by taskInDeal.CreatedByUserID
into groupedDemoClasses
select new TaskForNotification
{
Email = user.Email,
TaskInDealField1 = taskInDeal.TaskInDealField1,
TaskInDealField2 = taskInDeal.TaskInDealField2,
TaskInDealField3 = taskInDeal.TaskInDealField3,
...
}
).ToDictionary(gdc => gdc.Key, gdc => gdc.ToList());
}
So, to first query I need to join email from other table.
// do the date logic up front, not in the database.
DateTime now = DateTime.Now
DateTime weekFromNow = now.AddDays(7);
// pull the joined rows out of the database.
var rows =
(
from taskInDeal in db.TasksInDeals
where taskInDeal.Date > now && taskInDeal.Date < weekFromNow
join user in db.Users
on taskInDeal.CreatedByUserID equals user.UserID
select new {TaskInDeal = taskInDeal, UserEmail = user.Email}
).ToList();
// shape the rows in memory
Dictionary<int, List<TaskForNotification>> result =
(
from row in rows
let taskForNotification = new TaskForNotification
{
Email = row.UserEmail,
TaskInDealField1 = row.TaskInDeal.TaskInDealField1,
TaskInDealField2 = row.TaskInDeal.TaskInDealField2,
TaskInDealField3 = row.TaskInDeal.TaskInDealField3,
...
}
group taskForNotification by row.TaskInDeal.CreatedByUserID
// without an "into", group by ends the query.
).ToDictionary(g => g.Key, g => g.ToList());
When you group, bear this in mind. Groups in SQL have only keys and aggregates. Groups in LINQ have keys, aggregates and elements! If you ask the database for groups, and then ask for the elements - SQL couldn't provide you with those elements in a single query. You'll wind up automatically repeatedly re-querying using the group's key as a filter.
I have SQL database as follows
alt text http://img97.imageshack.us/img97/5774/dbimage.jpg
Now I want to filter the restaurant_detail table for the parameters:
1. cuisine 2. area
Can you help me to build LINQ query?
I presume you have a model generated either with LINQ to SQL or Entity Framework. Also, I'm assuming foreign key relationships have been set.
var details = db
.Cuisines
.Where(c => c.Cuisine=="something")
.SelectMany(c => c.RestaurantCuisines)
.Select(rc => rc.Restaurant.RestaurantDetails)
.Where(rd => rd.Area=="something")
;
Done with the linq query using following lines of code :
c = from q in dc.restaurant_cuisines
where q.cuisine.cuisine1.Contains(cuisine)
&& q.restaurant.price.ToString().Length == price.Length
select new NearBy { NearById = q.restaurant.id, NearByLongitude = (double)q.restaurant.longitude, NearByLatitude = (double)q.restaurant.latitude };
}
int[] ids = new int[c.Count()];
var lon = from q1 in dc.area_maps where q1.area.ToLower() == area.ToLower() select q1.longtitude;
var lat = from q1 in dc.area_maps where q1.area.ToLower() == area.ToLower() select q1.latitude;
foreach(NearBy n in c)
{
result = calcDistNew((double)lat.FirstOrDefault(), (double)lon.FirstOrDefault(), n.NearByLatitude, n.NearByLongitude);
ids[i++] = n.NearById;
}
var r = from q in dc.restaurant_details
where 1 == 1 &&
(ids).Contains(q.restaurant_id)
select new Restaurant
{
Restora_id = q.restaurant_id.ToString(),
Name = q.restaurant.name,
Foodtype = q.restaurant.foodtype.foodtype1,
Avg_rating = q.restaurant.avg_rating.ToString(),
Featured = q.restaurant.featured.ToString(),
CuisineList = getCuisine(q.restaurant_id),
Restora_type = q.type,
Distance = Math.Round(calcDistNew((double)lat.FirstOrDefault(), (double)lon.FirstOrDefault(), (double)q.restaurant.latitude, (double)q.restaurant.longitude), 2),
Newarrival = q.restaurant.newarrival.ToString(),
CountRecord = ids.Length.ToString()
};
var d = r.AsEnumerable().OrderBy(t => t.Distance);
var g = d.Take(recordSize + 10).Skip(recordSize);
return g.ToList();
Please note that above displayed code generated with some changes from the initial requirements.