Linq query efficiency using Entity Framework - asp.net

Question

I have to rewrite a huge SQL query that gets data from around 10 tables using Entity Framework and Linq. In short, the query gets a list of products from the main table, then fetches other information like download count, sales count, author, etc. from other tables for those products.
What I decided to do was break it down into parts so that its easy for others to understand and edit.
First, I get the list of products. Then, I get a list data for the other columns and I merge everything together in the last step.
var mainTableQuery = from p in context.mains
select new
{
p.ProductID,
p.title,
p.department_id,
p.TotalInStock
};
//Getting the top author by priority for every product ID
var authorLinkQuery= from authorLink in context.AuthorLinks
group authorLink by authorLink.ProductID
into groups
select groups.OrderBy(p=>p.Priority).FirstOrDefault();
// Link productIDs with primary author names
var authorsFinalQuery = from author in context.Authors
join authorLink in authorLinkQuery
on author.AuthorID equals authorLink.AuthorID
select new
{
authorLink.ProductID,
Name = (String.IsNullOrEmpty(author.Company) ? author.FirstName + " " + author.LastName : author.Company)
};
var finalQuery = from main in mainTableQuery
join author in authorsFinalQuery
on main.ProductID equals author.ProductID
select new
{
main,
author.Name
};
This final query gets the correct data but it takes around 30s. The original SQL server query took only 6s. The problem is that the SQL server query that is generated by entity framework is very inefficient. Is there a way to optimize this?
EDIT: The complete stored procedure that I'm trying to replace is:
CREATE PROCEDURE [dbo].[usp_AllProducts] (#ProgramAreaID int,
#CustomDateStart datetime,
#CustomDateEnd datetime,
#ShowNLA nvarchar(50))
AS
BEGIN
SET NOCOUNT ON;
IF #ProgramAreaID = 1000
BEGIN
SELECT TOP (100) PERCENT
BaseInventory.ProductID,
BaseInventory.ReferenceNumber,
BaseInventory.Title,
BaseInventory.StoredBy,
BaseInventory.TotalInStock,
BaseInventory.StockAtEDC,
BaseInventory.Cost,
BaseInventory.RetailPrice,
BaseInventory.PubDate,
BaseInventory.DepartmentCode,
vwAuthor.PrimaryAuthor,
ISNULL(Sales30Days.QuantitySold, 0) AS Last30Days,
ISNULL(SalesPastYear.QuantitySold, 0) AS Last365Days,
ISNULL(CustomRangeSales.QuantitySold, 0) AS CustomRange,
ISNULL(SalesPastYear.ZeroStock, '12/31/9999') AS ZeroStock,
ISNULL(SalesPastYear.ZeroStockFullDate, CONVERT(datetime, '12/31/9999', 102)) AS ZeroStockFullDate,
BaseInventory.FullPubDate,
BaseInventory.ProgramArea,
BaseInventory.Spaces,
BaseInventory.DigitalFileExists,
BaseInventory.DownloadCount,
BaseInventory.DownloadCountCustom,
ISNULL(SalesPastYear.SpacesSold, 0.000) AS SpacesSold,
BaseInventory.DateReceived,
BaseInventory.ProductWeight,
BaseInventory.NumberOfPages,
BaseInventory.DigitalFileCount,
BaseInventory.ActiveDigitalFileCount
FROM (SELECT TOP (100) PERCENT
m.ProductWeight,
m.ProductID,
m.reference_number AS ReferenceNumber,
m.title AS Title,
MAX(sb.StoredBy) AS StoredBy,
m.TotalInStock,
m.edc_copies AS StockAtEDC,
m.pub_cost AS Cost,
m.RetailPrice,
m.pub_date AS PubDate,
d.department_code AS DepartmentCode,
m.department_id AS DepartmentId,
dg.department_group AS ProgramArea,
m.FullPubDate,
ISNULL(Boxes.Spaces, CASE
WHEN sb.StoredBy = 'WWW' THEN 0
ELSE 1
END) AS Spaces,
CASE
WHEN ISNULL(dm.FileID, 0) = 0 THEN 'N/A'
ELSE 'Active'
END AS DigitalFileExists,
ISNULL(DLs.DownloadCount, 0) AS DownloadCount,
ISNULL(DLsCustom.DownloadCountCustom, 0) AS DownloadCountCustom,
MAX(history.DateReceived) AS DateReceived,
ISNULL(m.number_of_pages, 'N/A') AS NumberOfPages,
(SELECT
COUNT(*)
FROM tblDigitalMedia tD
WHERE tD.ProductID = m.ProductID)
AS DigitalFileCount,
(SELECT
COUNT(*)
FROM tblDigitalMedia tD
WHERE tD.ProductID = m.ProductID
AND tD.Active = 1)
AS ActiveDigitalFileCount
FROM dbo.main m
INNER JOIN dbo.departments d
ON m.department_id = d.department_id
INNER JOIN dbo.department_groups dg
ON d.department_group_id = dg.department_group_id
/* InventoryTemp should be called InventoryByLocation */
LEFT OUTER JOIN (SELECT
m1.ProductID,
SUM(ISNULL(it.NumberOfBoxes, 0)) + 1 AS Spaces
FROM dbo.main AS m1
INNER JOIN dbo.InventoryTemp AS it
ON m1.ProductID = it.ProductID
GROUP BY m1.ProductID) AS Boxes
ON m.ProductID = Boxes.ProductID
/* JobsTemp should be called JobHistory */
LEFT OUTER JOIN dbo.JobsTemp history
ON m.ProductID = history.ProductID
LEFT OUTER JOIN (
/* If dates are null then fetch for previous year. */
SELECT TOP (100) PERCENT
dm1.ProductID,
COUNT(dl1.TimeStamp) AS DownloadCountCustom
FROM dbo.tblDigitalMedia AS dm1
LEFT OUTER JOIN dbo.tblDigitalMediaDownloads dl1
ON dm1.FileID = dl1.FileID
WHERE ((#CustomDateStart IS NOT NULL)
AND (dl1.TimeStamp >= #CustomDateStart)
AND (dl1.TimeStamp <= #CustomDateEnd))
OR ((#CustomDateStart IS NULL)
AND (dl1.TimeStamp BETWEEN DATEADD(D, -365, GETDATE()) AND GETDATE()))
GROUP BY dm1.ProductID) AS DLsCustom
ON m.ProductID = DLsCustom.ProductID
LEFT OUTER JOIN (
/* If dates are null then fetch for previous year. */
SELECT TOP (100) PERCENT
dm2.ProductID,
COUNT(dl2.TimeStamp) AS DownloadCount
FROM dbo.tblDigitalMedia AS dm2
LEFT OUTER JOIN dbo.tblDigitalMediaDownloads dl2
ON dm2.FileID = dl2.FileID
WHERE dl2.TimeStamp BETWEEN DATEADD(D, -365, GETDATE()) AND GETDATE()
GROUP BY dm2.ProductID) AS DLs
ON m.ProductID = DLs.ProductID
LEFT OUTER JOIN dbo.tblDigitalMedia AS dm
ON m.ProductID = dm.ProductID
/* InventoryTemp should be called InventoryByLocation */
LEFT OUTER JOIN dbo.InventoryTemp it2
ON m.ProductID = it2.ProductID
INNER JOIN dbo.StoredBy sb
ON m.StoredByID = sb.StoredByID
WHERE (m.edc_isle LIKE N'Aisle' + N'%'
OR m.edc_isle = N'Digital Media'
OR m.edc_isle = N'Duplicator')
AND NOT (d.department_id BETWEEN 995 AND 999)
GROUP BY m.ProductWeight,
m.ProductID,
m.reference_number,
m.title,
m.TotalInStock,
dg.department_group_id,
m.pub_date,
m.department_id,
d.department_code,
m.pub_cost,
m.RetailPrice,
m.FullPubDate,
m.edc_isle,
sb.StoredBy,
dg.department_group,
CASE
WHEN ISNULL(dm.FileID, 0) = 0 THEN 'N/A'
ELSE 'Active'
END,
ISNULL(DLs.DownloadCount, 0),
ISNULL(DLsCustom.DownloadCountCustom, 0),
ISNULL(Boxes.Spaces, CASE
WHEN sb.StoredBy = 'WWW' THEN 0
ELSE 1
END),
m.edc_copies,
ISNULL(m.number_of_pages, 'N/A')
HAVING (NOT (MAX(sb.StoredBy) = #ShowNLA))
ORDER BY m.FullPubDate) AS BaseInventory /* ***** Table A ***** */
LEFT OUTER JOIN (SELECT
dbo.shopping_cart.ProductID,
SUM(dbo.shopping_cart.quantity) AS QuantitySold
FROM dbo.orders
INNER JOIN dbo.shopping_cart
ON dbo.orders.receiving_number = dbo.shopping_cart.receiving_number
WHERE dbo.orders.OrderTimeStamp >= DATEADD(DAY, -30, GETDATE())
AND dbo.orders.OrderTimeStamp < GETDATE()
AND dbo.shopping_cart.ProductID IS NOT NULL
GROUP BY dbo.shopping_cart.ProductID) AS Sales30Days /* ***** Table B ***** */
ON BaseInventory.ProductID = Sales30Days.ProductID
LEFT OUTER JOIN (SELECT
dbo.shopping_cart.ProductID,
SUM(dbo.shopping_cart.quantity) AS QuantitySold
FROM dbo.orders
INNER JOIN dbo.shopping_cart
ON dbo.orders.receiving_number = dbo.shopping_cart.receiving_number
WHERE #CustomDateStart IS NOT NULL
AND dbo.orders.OrderTimeStamp >= #CustomDateStart
AND dbo.orders.OrderTimeStamp <= #CustomDateEnd
AND dbo.shopping_cart.ProductID IS NOT NULL
GROUP BY dbo.shopping_cart.ProductID) AS CustomRangeSales /* ***** CustomRangeSales ***** */
ON BaseInventory.ProductID = CustomRangeSales.ProductID
LEFT OUTER JOIN (SELECT TOP (100) PERCENT
cart3.ProductID,
SUM(cart3.quantity) AS QuantitySold,
m3.TotalInStock,
CASE
WHEN
CONVERT(int, m3.TotalInStock / (CONVERT(decimal(18, 10), SUM(cart3.quantity)) / 365)) > ((9999 - YEAR(GETDATE())) * 365) THEN NULL
ELSE CONVERT(varchar, DATEADD(DAY, CONVERT(int, m3.TotalInStock / (CONVERT(decimal(18, 10), SUM(cart3.quantity)) / 365)), GETDATE()), 101)
END AS ZeroStock,
CASE
WHEN
CONVERT(int, m3.TotalInStock / (CONVERT(decimal(18, 10), SUM(cart3.quantity)) / 365)) > ((9999 - YEAR(GETDATE())) * 365) THEN NULL
ELSE DATEADD(DAY, CONVERT(int, m3.TotalInStock / (CONVERT(decimal(18, 10), SUM(cart3.quantity)) / 365)), GETDATE())
END AS ZeroStockFullDate,
CONVERT(decimal(18, 3), SUM(cart3.quantity) / ISNULL(CONVERT(decimal(18, 2), AvgInventory.NumberPerBox), SUM(cart3.quantity) + m3.TotalInStock)) AS SpacesSold,
AvgInventory.NumberPerBox
FROM dbo.orders AS o1
INNER JOIN dbo.shopping_cart AS cart3
ON o1.receiving_number = cart3.receiving_number
INNER JOIN dbo.main AS m3
ON cart3.ProductID = m3.ProductID
LEFT OUTER JOIN (SELECT TOP (100) PERCENT
ProductID,
AVG(NumberPerBox) AS NumberPerBox
FROM dbo.InventoryTemp
GROUP BY ProductID
ORDER BY ProductID) AS AvgInventory
ON m3.ProductID = AvgInventory.ProductID
WHERE (o1.OrderTimeStamp BETWEEN DATEADD(DAY, -365, GETDATE()) AND GETDATE() + 1)
GROUP BY cart3.ProductID,
m3.TotalInStock,
AvgInventory.NumberPerBox
HAVING (NOT (cart3.ProductID IS NULL))) AS SalesPastYear /* ***** Table C ***** */
ON BaseInventory.ProductID = SalesPastYear.ProductID
LEFT OUTER JOIN (SELECT
ProductID,
CASE
WHEN ((Auth.Company = '') OR
(Auth.Company IS NULL)) THEN LTRIM(ISNULL(Auth.FirstName, '') + ' ' + ISNULL(Auth.LastName, ''))
ELSE Auth.Company
END AS PrimaryAuthor
FROM dbo.Author AS Auth
INNER JOIN (SELECT
AUTHLINK.AuthorID,
AUTHLINK.Priority,
AUTHLINK.ProductID
FROM (SELECT TOP (100) PERCENT
ProductID,
MIN(ISNULL(Priority, 0)) AS Priority
FROM dbo.AuthorLink
GROUP BY ProductID
ORDER BY ProductID) AS AuthMinPrty
INNER JOIN dbo.AuthorLink AS AUTHLINK
ON (AuthMinPrty.ProductID = AUTHLINK.ProductID)
AND (ISNULL(AuthMinPrty.Priority, 0) = ISNULL(AUTHLINK.Priority, 0))) AS PrimaryAuthor
ON Auth.AuthorID = PrimaryAuthor.AuthorID) AS vwAuthor /* Table Author */
ON BaseInventory.ProductID = vwAuthor.ProductID
ORDER BY BaseInventory.ReferenceNumber
END
ELSE
BEGIN
SELECT TOP (100) PERCENT
BaseInventory.ProductID,
BaseInventory.ReferenceNumber,
BaseInventory.Title,
BaseInventory.StoredBy,
BaseInventory.TotalInStock,
BaseInventory.StockAtEDC,
BaseInventory.Cost,
BaseInventory.RetailPrice,
BaseInventory.PubDate,
BaseInventory.DepartmentCode,
vwAuthor.PrimaryAuthor,
ISNULL(Sales30Days.QuantitySold, 0) AS Last30Days,
ISNULL(SalesPastYear.QuantitySold, 0) AS Last365Days,
ISNULL(CustomRangeSales.QuantitySold, 0) AS CustomRange,
ISNULL(SalesPastYear.ZeroStock, '12/31/9999') AS ZeroStock,
ISNULL(SalesPastYear.ZeroStockFullDate, CONVERT(datetime, '12/31/9999', 102)) AS ZeroStockFullDate,
BaseInventory.FullPubDate,
BaseInventory.ProgramArea,
BaseInventory.Spaces,
BaseInventory.DigitalFileExists,
BaseInventory.DownloadCount,
BaseInventory.DownloadCountCustom,
ISNULL(SalesPastYear.SpacesSold, 0.000) AS SpacesSold,
BaseInventory.DateReceived,
BaseInventory.ProductWeight,
BaseInventory.NumberOfPages,
BaseInventory.DigitalFileCount,
BaseInventory.ActiveDigitalFileCount
FROM (SELECT TOP (100) PERCENT
m.ProductWeight,
m.ProductID,
m.reference_number AS ReferenceNumber,
m.title AS Title,
MAX(sb.StoredBy) AS StoredBy,
m.TotalInStock,
m.edc_copies AS StockAtEDC,
m.pub_cost AS Cost,
m.RetailPrice,
m.pub_date AS PubDate,
d.department_code AS DepartmentCode,
m.department_id AS DepartmentId,
dg.department_group AS ProgramArea,
m.FullPubDate,
ISNULL(Boxes.Spaces, CASE
WHEN sb.StoredBy = 'WWW' THEN 0
ELSE 1
END) AS Spaces,
CASE
WHEN ISNULL(dm.FileID, 0) = 0 THEN 'N/A'
ELSE 'Active'
END AS DigitalFileExists,
ISNULL(DLs.DownloadCount, 0) AS DownloadCount,
ISNULL(DLsCustom.DownloadCountCustom, 0) AS DownloadCountCustom,
MAX(history.DateReceived) AS DateReceived,
ISNULL(m.number_of_pages, 'N/A') AS NumberOfPages,
(SELECT
COUNT(*)
FROM tblDigitalMedia tD
WHERE tD.ProductID = m.ProductID)
AS DigitalFileCount,
(SELECT
COUNT(*)
FROM tblDigitalMedia tD
WHERE tD.ProductID = m.ProductID
AND tD.Active = 1)
AS ActiveDigitalFileCount
FROM dbo.main m
INNER JOIN dbo.departments d
ON m.department_id = d.department_id
INNER JOIN dbo.department_groups dg
ON d.department_group_id = dg.department_group_id
/* InventoryTemp should be called InventoryByLocation */
LEFT OUTER JOIN (SELECT
m1.ProductID,
SUM(ISNULL(it.NumberOfBoxes, 0)) + 1 AS Spaces
FROM dbo.main AS m1
INNER JOIN dbo.InventoryTemp AS it
ON m1.ProductID = it.ProductID
GROUP BY m1.ProductID) AS Boxes
ON m.ProductID = Boxes.ProductID
/* JobsTemp should be called JobHistory */
LEFT OUTER JOIN dbo.JobsTemp history
ON m.ProductID = history.ProductID
LEFT OUTER JOIN (
/* If dates are null then fetch for previous year. */
SELECT TOP (100) PERCENT
dm1.ProductID,
COUNT(dl1.TimeStamp) AS DownloadCountCustom
FROM dbo.tblDigitalMedia AS dm1
LEFT OUTER JOIN dbo.tblDigitalMediaDownloads dl1
ON dm1.FileID = dl1.FileID
WHERE ((#CustomDateStart IS NOT NULL)
AND (dl1.TimeStamp >= #CustomDateStart)
AND (dl1.TimeStamp <= #CustomDateEnd))
OR ((#CustomDateStart IS NULL)
AND (dl1.TimeStamp BETWEEN DATEADD(D, -365, GETDATE()) AND GETDATE()))
GROUP BY dm1.ProductID) AS DLsCustom
ON m.ProductID = DLsCustom.ProductID
LEFT OUTER JOIN (
/* If dates are null then fetch for previous year. */
SELECT TOP (100) PERCENT
dm2.ProductID,
COUNT(dl2.TimeStamp) AS DownloadCount
FROM dbo.tblDigitalMedia AS dm2
LEFT OUTER JOIN dbo.tblDigitalMediaDownloads dl2
ON dm2.FileID = dl2.FileID
WHERE dl2.TimeStamp BETWEEN DATEADD(D, -365, GETDATE()) AND GETDATE()
GROUP BY dm2.ProductID) AS DLs
ON m.ProductID = DLs.ProductID
LEFT OUTER JOIN dbo.tblDigitalMedia AS dm
ON m.ProductID = dm.ProductID
/* InventoryTemp should be called InventoryByLocation */
LEFT OUTER JOIN dbo.InventoryTemp it2
ON m.ProductID = it2.ProductID
INNER JOIN dbo.StoredBy sb
ON m.StoredByID = sb.StoredByID
WHERE (m.edc_isle LIKE N'Aisle' + N'%'
OR m.edc_isle = N'Digital Media'
OR m.edc_isle = N'Duplicator')
AND (dg.department_group_id = #ProgramAreaID)
GROUP BY m.ProductWeight,
m.ProductID,
m.reference_number,
m.title,
m.TotalInStock,
dg.department_group_id,
m.pub_date,
m.department_id,
d.department_code,
m.pub_cost,
m.RetailPrice,
m.FullPubDate,
m.edc_isle,
sb.StoredBy,
dg.department_group,
CASE
WHEN ISNULL(dm.FileID, 0) = 0 THEN 'N/A'
ELSE 'Active'
END,
ISNULL(DLs.DownloadCount, 0),
ISNULL(DLsCustom.DownloadCountCustom, 0),
ISNULL(Boxes.Spaces, CASE
WHEN sb.StoredBy = 'WWW' THEN 0
ELSE 1
END),
m.edc_copies,
ISNULL(m.number_of_pages, 'N/A')
HAVING (NOT (MAX(sb.StoredBy) = #ShowNLA))
ORDER BY m.FullPubDate) AS BaseInventory /* ***** Table A ***** */
LEFT OUTER JOIN (SELECT
dbo.shopping_cart.ProductID,
SUM(dbo.shopping_cart.quantity) AS QuantitySold
FROM dbo.orders
INNER JOIN dbo.shopping_cart
ON dbo.orders.receiving_number = dbo.shopping_cart.receiving_number
WHERE dbo.orders.OrderTimeStamp >= DATEADD(DAY, -30, GETDATE())
AND dbo.orders.OrderTimeStamp < GETDATE()
AND dbo.shopping_cart.ProductID IS NOT NULL
GROUP BY dbo.shopping_cart.ProductID) AS Sales30Days /* ***** Table B ***** */
ON BaseInventory.ProductID = Sales30Days.ProductID
LEFT OUTER JOIN (SELECT
dbo.shopping_cart.ProductID,
SUM(dbo.shopping_cart.quantity) AS QuantitySold
FROM dbo.orders
INNER JOIN dbo.shopping_cart
ON dbo.orders.receiving_number = dbo.shopping_cart.receiving_number
WHERE #CustomDateStart IS NOT NULL
AND dbo.orders.OrderTimeStamp >= #CustomDateStart
AND dbo.orders.OrderTimeStamp <= #CustomDateEnd
AND dbo.shopping_cart.ProductID IS NOT NULL
GROUP BY dbo.shopping_cart.ProductID) AS CustomRangeSales /* ***** CustomRangeSales ***** */
ON BaseInventory.ProductID = CustomRangeSales.ProductID
LEFT OUTER JOIN (SELECT TOP (100) PERCENT
cart3.ProductID,
SUM(cart3.quantity) AS QuantitySold,
m3.TotalInStock,
CASE
WHEN
CONVERT(int, m3.TotalInStock / (CONVERT(decimal(18, 10), SUM(cart3.quantity)) / 365)) > ((9999 - YEAR(GETDATE())) * 365) THEN NULL
ELSE CONVERT(varchar, DATEADD(DAY, CONVERT(int, m3.TotalInStock / (CONVERT(decimal(18, 10), SUM(cart3.quantity)) / 365)), GETDATE()), 101)
END AS ZeroStock,
CASE
WHEN
CONVERT(int, m3.TotalInStock / (CONVERT(decimal(18, 10), SUM(cart3.quantity)) / 365)) > ((9999 - YEAR(GETDATE())) * 365) THEN NULL
ELSE DATEADD(DAY, CONVERT(int, m3.TotalInStock / (CONVERT(decimal(18, 10), SUM(cart3.quantity)) / 365)), GETDATE())
END AS ZeroStockFullDate,
CONVERT(decimal(18, 3), SUM(cart3.quantity) / ISNULL(CONVERT(decimal(18, 2), AvgInventory.NumberPerBox), SUM(cart3.quantity) + m3.TotalInStock)) AS SpacesSold,
AvgInventory.NumberPerBox
FROM dbo.orders AS o1
INNER JOIN dbo.shopping_cart AS cart3
ON o1.receiving_number = cart3.receiving_number
INNER JOIN dbo.main AS m3
ON cart3.ProductID = m3.ProductID
LEFT OUTER JOIN (SELECT TOP (100) PERCENT
ProductID,
AVG(NumberPerBox) AS NumberPerBox
FROM dbo.InventoryTemp
GROUP BY ProductID
ORDER BY ProductID) AS AvgInventory
ON m3.ProductID = AvgInventory.ProductID
WHERE (o1.OrderTimeStamp BETWEEN DATEADD(DAY, -365, GETDATE()) AND GETDATE() + 1)
GROUP BY cart3.ProductID,
m3.TotalInStock,
AvgInventory.NumberPerBox
HAVING (NOT (cart3.ProductID IS NULL))) AS SalesPastYear /* ***** Table C ***** */
ON BaseInventory.ProductID = SalesPastYear.ProductID
LEFT OUTER JOIN (SELECT
ProductID,
CASE
WHEN ((Auth.Company = '') OR
(Auth.Company IS NULL)) THEN LTRIM(ISNULL(Auth.FirstName, '') + ' ' + ISNULL(Auth.LastName, ''))
ELSE Auth.Company
END AS PrimaryAuthor
FROM dbo.Author AS Auth
INNER JOIN (SELECT
AUTHLINK.AuthorID,
AUTHLINK.Priority,
AUTHLINK.ProductID
FROM (SELECT TOP (100) PERCENT
ProductID,
MIN(ISNULL(Priority, 0)) AS Priority
FROM dbo.AuthorLink
GROUP BY ProductID
ORDER BY ProductID) AS AuthMinPrty
INNER JOIN dbo.AuthorLink AS AUTHLINK
ON (AuthMinPrty.ProductID = AUTHLINK.ProductID)
AND (ISNULL(AuthMinPrty.Priority, 0) = ISNULL(AUTHLINK.Priority, 0))) AS PrimaryAuthor
ON Auth.AuthorID = PrimaryAuthor.AuthorID) AS vwAuthor /* Table Author */
ON BaseInventory.ProductID = vwAuthor.ProductID
ORDER BY BaseInventory.ReferenceNumber
END
END /* stored procedure */
GO

Answer 1

Ignore all the people who are telling you to do it some other way, and see whether you can tune what you have. The person who claimed this is 4 queries is incorrect. The LINQ will compose into a single SQL statement. What you need to do is to try and find out:
What the generated SQL looks like (try capturing it using SQL Server Profiler)
Why it is inefficient (again, SQL Server Profiler, or paste into SSMS and show the query plan)
Once you have done that, it may become clearer what you need to do to your LINQ to make it perform.
One thing you could try in order simplify the amount you need to look at at one time: Execute each "inner" query in isolation and see whether any of them look bad by themselves.