Hi I need some help coverting this sql statement to Linq, I am very new to Linq and LinqToSql, and this is my weakness, it seems like this is used frequently and I need to wrap my brain around the syntax. The Code is below.
select distinct t1.Color from [ProductAttributes] t1 join [Product] t2 on t1.Name = t2.ProductName where t1.ProductID = #productID order by t1.color
#productID is the parameter coming into the function, where I am trying to use Linq in MVC.
Thanks
It might be like this I guess
int myProductID = 1;//or whatever id you want.
MyDataContext mdc = new MyDataContext(CONNECTION_STRING_IF_NEEDED);
//MyDataContext is your datacontext generated by LinqToSql
var result = (from x in mdc.ProductAttributes
join y in Products on x.Name.equals(y.ProductName)
where x.ProductID = myProductID
orderby x.color
select x.Color).Distinct();
Note That Table names might need to be fixed.
This is the query i am running:
select /*+ index(V_AMV_PLG_ORDER_HISTORY_200_MS.orders.T0 IDX_ORDER_VERSION_3) */ *
from V_AMV_PLG_ORDER_HISTORY_200_MS
where EXCHANGE_SK = 32 and PRODUCT_SK = 1000169
And it uses a different index than the one i am ordering it to.
As you can see, I am querying from the view V_AMV_PLG_ORDER_HISTORY_200_MS, you can see its sql query here:
V_AMV_PLG_ORDER_HISTORY_200_MS view SQL Query:
SELECT AMV_PERF_PROFILES_FRONTEND.AMV_PLG_GET_SEGMENT(200, orders.ORDER_GLOBAL_DATE_TIME) AS ORDER_DATE_TIME,
SUM(orders.BASE_VOLUME) AS VOLUME,
SUM(orders.BASE_CURR_LIMIT_PRICE*orders.BASE_VOLUME)/SUM(orders.BASE_VOLUME) AS PRICE,
orders.PRODUCT_SK AS PRODUCT_SK,
orders.EXCHANGE_SK AS EXCHANGE_SK,
orders.DIRECTION_CD AS DIRECTION_CD,
orders.AGG_UNIT_CD AS AGG_UNIT_CD,
orders.TRADER_KEY AS EXECUTING_REPRESENTATIVE_KEY,
orders.ACCOUNT_KEY AS ACCOUNT_KEY,
a.BUSINESS_UNIT_CD AS BUSINESS_UNIT_CD
FROM AMV_PERF_PROFILES_FRONTEND.S_AMV_ORDER_VERSION_NEW orders
INNER JOIN AMV_PERF_PROFILES_FRONTEND.S_AMV_ACCOUNT a
ON a.ACCOUNT_KEY = orders.ACCOUNT_KEY
WHERE BASE_VOLUME > 0
GROUP BY AMV_PERF_PROFILES_FRONTEND.AMV_PLG_GET_SEGMENT(200, orders.ORDER_GLOBAL_DATE_TIME),
orders.PRODUCT_SK,
orders.EXCHANGE_SK,
orders.ACCOUNT_KEY,
a.BUSINESS_UNIT_CD,
orders.AGG_UNIT_CD,
orders.TRADER_KEY,
orders.DIRECTION_CD;
He is getting the data using the Synonym S_AMV_ORDER_VERSION_NEW, Which directs to another Scheme, to a view called V_AMV_ORDER_VERSION and refering to it as orders, its sql query here:
V_AMV_ORDER_VERSION view Sql query:
SELECT T1.ENTITY_KEY ,
T2.AGG_UNIT_CD ,
T0.BASE_CURR_LIMIT_PRICE ,
T7.DIRECTION_CD ,
T0.EXCHANGE_SK,
T0.ORDER_LOCAL_DATE_TIME ,
T0.PRODUCT_SK,
T18.ENTITY_KEY ,
T19.ENTITY_KEY ,
T0.NOTIONAL_VALUE2 ,
T0.NOTIONAL_VALUE ,
T0.ORDER_GLOBAL_DATE_TIME ,
T0.BASE_VOLUME ,
T31.TRANSACTION_STATUS_CD ,
T0.ORDER_VERSION_KEY
FROM ETS_UDM_CDS_NEW.ORDER_VERSION T0
LEFT OUTER JOIN ETS_UDM_CDS_NEW.ENTITY T1
ON T0.ACCOUNT_SK = T1.ENTITY_SK
LEFT OUTER JOIN ETS_UDM_CDS_NEW.AGG_UNIT T2
ON T0.AGG_UNIT_SK = T2.ENTITY_SK
LEFT OUTER JOIN ETS_UDM_CDS_NEW.DIRECTION T7
ON T0.DIRECTION_SK = T7.ENTITY_SK
LEFT OUTER JOIN ETS_UDM_CDS_NEW.ENTITY T18
ON T0.LOCAL_TIME_ZONE_SK = T18.ENTITY_SK
LEFT OUTER JOIN ETS_UDM_CDS_NEW.ENTITY T19
ON T0.TRADER_SK = T19.ENTITY_SK
LEFT OUTER JOIN ETS_UDM_CDS_NEW.TRANSACTION_STATUS T31
ON T0.TRANSACTION_STATUS_SK = T31.ENTITY_SK;
Which takes its data from a table called ORDER_VERSION and refers to it as T0
this table has an index called IDX_ORDER_VERSION
The problem is that oracle ignores my hint, And uses a different index, Now, I have managed to use a hint to make oracle use an index i wanted when i was querying a view that gets data from a table, But this time I am querying a view which gets his data from another view which gets his data from a table.
And also, The second view in the line is on a different Scheme and i am using a synonym, So perhaps that is why i am missing something Cuz i tried many combinations of possible solutions i found on google but nothing seems to be working...
I would say that if i go one step forward and query directly from V_AMV_ORDER_VERSION (Without the synonym) IT works and i can make oracle work with any index i want, so this query works perfect:
select /*+ index(orders.T0 IDX_ORDER_VERSION_5) */ * from V_AMV_ORDER_VERSION orders
where EXCHANGE_SK =32 and PRODUCT_SK = 1000169
Well me and our company's DBA looked at it for a while, it seems like an Oracle bug in the Global Hint manifestation, We have created the view V_AMV_PLG_ORDER_HISTORY_200_MS using a regular join rather than an ANSI join, and now it works properly:
V_AMV_PLG_ORDER_HISTORY_200_MS view SQL Query:
SELECT AMV_PERF_PROFILES_FRONTEND.AMV_PLG_GET_SEGMENT(200, orders.ORDER_GLOBAL_DATE_TIME) AS ORDER_DATE_TIME,
SUM(orders.BASE_VOLUME) AS VOLUME,
SUM(orders.BASE_CURR_LIMIT_PRICE*orders.BASE_VOLUME)/SUM(orders.BASE_VOLUME) AS PRICE,
orders.PRODUCT_SK AS PRODUCT_SK,
orders.EXCHANGE_SK AS EXCHANGE_SK,
orders.DIRECTION_CD AS DIRECTION_CD,
orders.AGG_UNIT_CD AS AGG_UNIT_CD,
orders.TRADER_KEY AS EXECUTING_REPRESENTATIVE_KEY,
orders.ACCOUNT_KEY AS ACCOUNT_KEY,
a.BUSINESS_UNIT_CD AS BUSINESS_UNIT_CD
FROM AMV_PERF_PROFILES_FRONTEND.S_AMV_ORDER_VERSION_NEW orders,
AMV_PERF_PROFILES_FRONTEND.S_AMV_ACCOUNT a
WHERE BASE_VOLUME > 0 AND a.ACCOUNT_KEY = orders.ACCOUNT_KEY
GROUP BY AMV_PERF_PROFILES_FRONTEND.AMV_PLG_GET_SEGMENT(200, orders.ORDER_GLOBAL_DATE_TIME),
orders.PRODUCT_SK,
orders.EXCHANGE_SK,
orders.ACCOUNT_KEY,
a.BUSINESS_UNIT_CD,
orders.AGG_UNIT_CD,
orders.TRADER_KEY,
orders.DIRECTION_CD;
I have a list of strings (converted from Guid) that contains the ID's of items I want to pull from my table.
Then, in my LINQ query, I am trying to figure out how to do an in clause to pull records that are in that list.
Here is the LINQ
var RegionRequests = (from r in db.course_requests
where PendingIdList.Contains(r.request_state.ToString())
select r).ToList();
It builds, but I get a run error: "System.NotSupportedException: LINQ to Entities does not recognize the method 'System.String ToString()' method, and this method cannot be translated into a store expression".
I would prefer to compare guid to guid, but that gets me nowhere.
Can this be converted to a lambda expression? If that is best, how?
LINQ to Entites tries to convert your expression to an SQL Statement. Your server didn't know the stored procedure ToString().
Fix:
var regionRequests =
from r in db.course_requests.ToList()
where PendingIdList.Contains(r.request_state.ToString())
select r;
With db.course_requests.ToList() you force LINQ to materialize your database data (if big table, you gonna have a bad time) and the ToString() is executed in the object context.
You stated: I have a list of strings (converted from Guid) ...
Can you NOT convert them into strings and keep it as a List< System.Guid>?? Then you can do this (assuming PendingIdGuidList is List< System.Guid>:
var regionRequets = (from r in db.course_requests
join p in PendingIdGuidList on u.request_state equals p
select r).ToList();
Edited to add:
I ran a test on this using the following code:
var db = new EntityModels.MapleCreekEntities();
List<System.Guid> PendingIdGuidList =
new List<System.Guid>() {
System.Guid.Parse("77dfd79e-2d61-40b9-ac23-36eb53dc55bc"),
System.Guid.Parse("cd409b96-de92-4fd7-8870-aa42eb5b8751")
};
var regionRequets = (from r in db.Users
join p in PendingIdGuidList on r.Test equals p
select r).ToList();
Users is a table in my database. I added a column called Test as a Uniqueidentifier data type, then modified 2 records with the following Guids.
I know it's not exactly a 1:1 of what the OP is doing, but pretty close. Here is the profiled SQL statement:
SELECT
[Extent1].[ID] AS [ID],
[Extent1].[UserLogin] AS [UserLogin],
[Extent1].[Password] AS [Password],
[Extent1].[Test] AS [Test]
FROM [dbo].[Users] AS [Extent1]
INNER JOIN (SELECT
cast('77dfd79e-2d61-40b9-ac23-36eb53dc55bc' as uniqueidentifier) AS [C1]
FROM ( SELECT 1 AS X ) AS [SingleRowTable1]
UNION ALL
SELECT
cast('cd409b96-de92-4fd7-8870-aa42eb5b8751' as uniqueidentifier) AS [C1]
FROM ( SELECT 1 AS X ) AS [SingleRowTable2]) AS [UnionAll1] ON [Extent1].[Test] = [UnionAll1].[C1]
I have two entities: Master and Details.
When I query them, the resulting query to database is:
SELECT [Extent2]."needed columns listed here", [Extent1]."needed columns listed here"
FROM (SELECT * [Details]."all columns listed here"...
FROM [dbo].[Details] AS [Details]) AS [Extent1]
LEFT OUTER JOIN [dbo].[Master] AS [Extent2] ON [Extent1].[key] = [Extent2].[key]
WHERE [Extent1].[filterColumn] = #p__linq__0
My question is: why not the filter is in the inner query? How can I get this query? I've tried a lot of EF and Linq expressions.
What I need is something like:
SELECT <anything needed>
FROM Master LEFT JOIN Details ON Master.key = Details.Key
WHERE filterColumn = #param
I'm having a full sequential scan in both tables, and in my production environment, I have milions of rows in each table.
Thanks a lot !!
Sometimes The entity Framework does not produce the best query. You can do a few of the following to optimize.
Modify the linq statement (test with
LINQPad)
Create a stored proc and map the stored proc to return an entity
Create a view that handles the join and map the view to a new
entity
I have the following Linq statement:
(from order in Orders.AsEnumerable()
join component in Components.AsEnumerable()
on order.ORDER_ID equals component.ORDER_ID
join detail in Detailss.AsEnumerable()
on component.RESULT_ID equals detail.RESULT_ID
where orderRestrict.ORDER_MNEMONIC == "MyOrderText"
select new
{
Mnemonic = detail.TEST_MNEMONIC,
OrderID = component.ORDER_ID,
SeqNumber = component.SEQ_NUM
}).ToList()
I expect this to put out the following query:
select *
from Orders ord (NoLock)
join Component comp (NoLock)
on ord .ORDER_ID = comp.ORDER_ID
join Details detail (NoLock)
on comp.RESULT_TEST_NUM = detail .RESULT_TEST_NUM
where res.ORDER_MNEMONIC = 'MyOrderText'
but instead I get 3 seperate queries that select all rows from the tables. I am guessing that Linq is then filtering the values because I do get the correct values in the end.
The problem is that it takes WAY WAY too long because it is pulling down all the rows from all three tables.
Any ideas how I can fix that?
Remove the .AsEnumerable()s from the query as these are preventing the entire query being evaluated on the server.