is their a more efficient way of doing this?
set #ShippingL = (select ShippingL from AuctionProducts where ProductID = #ProductID)
set #ShippingB = (select ShippingB from AuctionProducts where ProductID = #ProductID)
set #ShippingH = (select ShippingH from AuctionProducts where ProductID = #ProductID)
set #ShippingW = (select ShippingW from AuctionProducts where ProductID = #ProductID)
Cheers,
-R
I would think doing one query would be as good as you'll get it:
select
#ShippingL = ShippingL,
#ShippingB = ShippingB,
#ShippingH = ShippingH,
#ShippingW = ShippingW
from
AuctionProducts
where
ProductID = #ProductID
I would imagine this is 4 times faster than the code that you posted. Also, make sure that you have an index defined on the ProductID column of the AuctionProducts table.
Related
I'm trying to merge three update statements into one.
"UPDATE DOT_WORKS SET START_DATE = :StartDate WHERE ID = :WorksId and END_DATE IS NULL;"
"UPDATE DOT_WORKS SET WORKS_TYPE = :WorksType WHERE ID = WorksId and WORKS_GROUP = :WorksGroup;"
"UPDATE DOT_WORKS SET WORKS_CONNECTION = :WorksConn WHERE ID = WorksId and WORKS_PLACE = :WorksPlace;"
I'm wondering whether there is a way to do that.
The reason why I'm trying to do so is to save the calls to database. It's more efficient to call db once instead of three.
Thanks!
UPDATE DOT_WORKS
SET START_DATE = case when END_DATE IS NULL then :StartDate else START_DATE end,
WORKS_TYPE = case when WORKS_GROUP = :WorksGroup then :WorksType else WORKS_TYPE end,
WORKS_CONNECTION = case when WORKS_PLACE = :WorksPlace then :WorksConn else WORKS_CONNECTION end
WHERE ID = :WorksId
and
(
END_DATE IS NULL OR
WORKS_GROUP = :WorksGroup OR
WORKS_PLACE = :WorksPlace
)
So I have few tables and i want inner join it information two create
new object. But I have a little bit trouble.
One my table have connection one to many, and when linq request , it
give me more result than i want , he just copy information. I need
request something like this:
IPagedList<HelperListings> srch = (from l in db.gp_listing
where l.DateCreated > weekago
join lp in db.gp_listing_photo on l.Id equals lp.ListingId
join loc in db.gp_location on l.LocationId equals loc.Id
orderby l.DateCreated ascending
select new HelperListings { id = l.Id, HouseNumber = l.HouseNumber,ListingPrice = l.ListingPrice, PhotoUrl = lp.PhotoUrl.First(), AreaStateCode = loc.AreaStateCode }).ToList().ToPagedList(page ?? 1, 15);
PhotoUrl = lp.PhotoUrl.First() i need something like this but i don`t have any ideas how to do it. Need ur help guys.
UPDATE :
Responding to your comment, you have at least 2 options : 1. use group by and select only the first PhotoUrl from each group, or 2. don't join to gp_listing_photo table to avoid duplicated rows, and use subquery to get only the first PhotoUrl. Example for the latter :
IPagedList<HelperListings> srch =
(from l in db.gp_listing
where l.DateCreated > weekago
join loc in db.gp_location on l.LocationId equals loc.Id
orderby l.DateCreated ascending
select new HelperListings
{
id = l.Id,
HouseNumber = l.HouseNumber,
ListingPrice = l.ListingPrice,
PhotoUrl = (from lp in db.gp_listing_photo where l.Id = lp.ListingId select lp.PhotoUrl).FirstOrDefault(),
AreaStateCode = loc.AreaStateCode
}
).ToList().ToPagedList(page ?? 1, 15);
How about simply appending .Distinct() after your LINQ query to avoid duplicated data :
IPagedList<HelperListings> srch =
(from l in db.gp_listing
where l.DateCreated > weekago
join lp in db.gp_listing_photo on l.Id equals lp.ListingId
join loc in db.gp_location on l.LocationId equals loc.Id
orderby l.DateCreated ascending
select new HelperListings
{
id = l.Id,
HouseNumber = l.HouseNumber,
ListingPrice = l.ListingPrice,
PhotoUrl = lp.PhotoUrl,
AreaStateCode = loc.AreaStateCode
}
).Distinct().ToList().ToPagedList(page ?? 1, 15);
For Reference : LINQ Select Distinct with Anonymous Types
I have a parent table, parentTable which may or may not have children in childTable. I am looking to get average % complete of any given parent's children, and the MAX(due) (date) of the children where they exist. My SQL is this:
SELECT parentRecord_id, assigned_to,
(SELECT avg(complete)
FROM childTable
WHERE parent_id = parentRecord_id
and deleted IS NULL
GROUP BY parent_id),
(SELECT max(due)
FROM childTable
WHERE parent_id = parentRecord_id
and deleted IS NULL
GROUP BY parent_id
)
FROM parentTable s
WHERE s.deleted IS NULL and assigned_to IS NOT NULL
My result set gives me rows with either correct values for the average and max, or null. In this instance I have to do follow up processing so I could ignore the null values if I was doing a foreach through DataTable rows. However I am trying to do this in Linq and can't figure out how to avoid a System.InvalidOperationException where Linq is trying to cast null to a double. Here is what I've tried so far.
var query8 = from s in db.parentTable
where s.deleted == null
select new
{
ID = s.assigned_to,
Average =
((from t in db.childTable
where t.parent_id == s.strategy_id
group t by new { t.parent_id } into g
select new
{
a0 = g.Average(f0 => f0.complete )
}).FirstOrDefault().a0)
};
foreach (var itm in query8)
{
Console.WriteLine(String.Format("User id:{0}, Average: {1}", itm.ID, itm.Average));
}
Here's my question. How do I get the query to handle those returned rows where average complete or max due (date) are null?
You can either filter out the records where the values are null (by another condition) or if you want to include them do something like this:
a0 = g.Average(f0 => f0.complete.HasValue? f0.complete: 0 )
I would cast the list to nullable double before calling Average/Max like so:
var query8 =
from s in db.parentTable
where s.deleted == null
select new
{
ID = s.assigned_to,
Average =
from t in db.childTable
where t.parent_id == s.strategy_id
group t by t.parent_id into g
select g.Cast<double?>().Average(f0 => f0.complete)
};
Assuming complete is a Nullable, you should be able to do:
var query8 = from s in db.parentTable
where s.deleted == null
select new
{
ID = s.assigned_to,
Average =
((from t in db.childTable
where t.parent_id == s.strategy_id
&& s.complete.HasValue()
group t by new { t.parent_id } into g
select new
{
a0 = g.Average(f0 => f0.complete )
}).FirstOrDefault().a0)
};
Thanks to all who responded.
I was unable get around the null anonymous issue with the basic query as I had it, but adding a join to the childTable eliminated the nulls.
Another solution is to use a from x in g.DefaultIfEmpty clause.
var query8 =
from st in db.tableParent
select new { Ass = st.assigned_to ,
Avg =
(from ta in db.tableChild
group ta by ta.parent_id into g
from x in g.DefaultIfEmpty()
select g.Average((f0=>f0.complete))).FirstOrDefault()
};
I am trying to select from multiple tables in an entity model. But there are two columns I would like to select and it's just not working out. The LINQ statement I have is:
var searchResult = from i in _imEntities.Issues
join dept in _imEntities.Departments
on i.Issued_to_dept equals dept.Dept_ID
where i.State == 1
select new {
i.ID_No,
i.Issue_Date,
Raised_By = dept.Dept_Name
.Where(i.Raised_by_Dept == dept.Dept_ID),
Issued_To = dept.Dept_Name
.Where(i.Issued_to_dept == dept.Dept_ID),
Details = i.Details
};
The column names are all correct, but I just can't get the dept_Names into the Raised_By and Issued_To fields. Is there another way to execute this?
Try this:
var query = from i in _imEntities.Issues
join dept_r in _imEntities.Departments
on i.Issued_to_dept equals dept_r.Dept_ID
join dept_i in _imEntities.Departments
on i.Issued_to_dept equals dept_i.Dept_ID
where i.State == 1
select new {
i.ID_No,
i.Issue_Date,
Raised_By = dept_r.Dept_Name,
Issued_To = dept_i.Dept_Name,
Details = i.Details
};
It's not clear what you are trying to achieve. But you definitely trying to apply where filter on single name string (also predicate syntax is not correct). Here is query which conditionally returns Dept_Name in Raised_By and Issued_To properties:
var query = from i in _imEntities.Issues
join dept in _imEntities.Departments
on i.Issued_to_dept equals dept.Dept_ID
where i.State == 1
select new {
i.ID_No,
i.Issue_Date,
Raised_By = (i.Raised_by_Dept == dept.Dept_ID) ? dept.Dept_Name : null,
Issued_To = (i.Issued_to_dept == dept.Dept_ID) ? dept.Dept_Name : null,
Details = i.Details
};
I am trying to convert this SQL to linq syntax, but I'm having some difficulties at that.
SELECT trans_date, count(*) FROM table1
GROUP BY trans_date
Result
01-01-2001 | 12
03-01-2001 | 45
var q = from a in table1
let dt = q.trans_date.value
group q by new {y = dt.Year.ToString(), m = dt.Month.ToString(), d = dt.Day.toString()}
into g
select new { int NumOf = g.Count(), DateTime TransDate = DateTime.Parse(g.Key.y + g.key.m + g.Key.d)}
This last "version" with the DateTime.Parse gives me a runtime error.
How to handle that the q.trans_date is a nullable DateTime and getting my resultset??
For one thing, you're not getting a runtime error with that code - you'll be getting a compile-time error as your code isn't valid C#.
Try this:
var q = from a in table1
group a by a.trans_date.value.Date into g
select new {
Count = g.Count(),
TransDate = g.Key
};