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  • LINQ TO SQL, Dynamic query with DATE type fields

    - by acanthus
    Hello, I'm building a query with the LINQ dynamic library so I don't know how many potential parameters will I have and I get an error when trying to query DATE type fields: Operator '=' incompatible with operand types 'DateTime' and 'String' When I step through the debugger in the Dynamic.cs it shows that the value is of type string and the field is of type date so the problem is obvious but I have no idea how to approach it. Any ideas? BR

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  • Translate LINQ to sql statement

    - by zielu1
    Hi, I want to translate LINQ expression tree to SQL statement and I don't want to write my own code for this. Example: var query = from c in Customers where c.Country == "UK" && c.City == "London" select c); To SELECT ... FROM Customers AS c WHERE c.Country = "UK" AND c.City = "London" I know DataContext.Log, but I want to use: query.ToSqlStatementString() Thanks

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  • Order by descending based on condition

    - by Vinni
    Hello All, I want to write a LINQ to Entity query which does order by ascending or descending based on input parameter, Is there any way for that. Following is the my code. Please suggest. public List<Hosters_HostingProviderDetail> GetPendingApproval(SortOrder sortOrder) { List<Hosters_HostingProviderDetail> returnList = new List<Hosters_HostingProviderDetail>(); int pendingStateId = Convert.ToInt32(State.Pending); //If the sort order is ascending if (sortOrder == SortOrder.ASC) { var hosters = from e in context.Hosters_HostingProviderDetail where e.ActiveStatusID == pendingStateId orderby e.HostingProviderName ascending select e; returnList = hosters.ToList<Hosters_HostingProviderDetail>(); return returnList; } else { var hosters = from e in context.Hosters_HostingProviderDetail where e.StateID == pendingStateId orderby e.HostingProviderName descending select e; returnList = hosters.ToList<Hosters_HostingProviderDetail>(); return returnList; } }

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  • Repository vs Data Access

    - by vdh_ant
    Hi guys In the context of the n-tier application, is there a difference between what you would consider your data access classes to be and your repositories? I tend to think yes but I just wanted to see what other thought. My thinking is that the job of the repository is just to contain and execute the raw query itself, where as the data access class would create the context, execute the repository (passing in the context), handle mapping the data model to the domain model and return the result back up... What do you guys think? Also do you see any of this changing in a Linq to XML scenario (assuming that you change the context for the relevant XDocument)? Cheers Anthony

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  • SQL Server to sql server linked server setup

    - by ScottStonehouse
    Please explain what is required to set up a SQL Server linked server. Server A is SQL 2005 windows logins only Server B is the same (SQL 2005 windows logins only) Server A runs windows XP Server B runs Windows Server 2003 Both SQL Server services are running under the same domain account. I am logged into my workstation with a domain account that has administrative rights on both SQL Servers. Note these are both SQL Server 2005 SP2 - I've had old hotfixes pointed out to me, but those are already applied. The issue I am having is this error: "Login failed for user 'NT AUTHORITY\ANONYMOUS LOGON'. (Microsoft SQL Server, Error: 18456)"

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  • Using SQL Server specific code in Access linked to SQL Server database

    - by Brennan Vincent
    Hi, I have an access file that is linked (through an ODBC connection) to a SQL Server 2008 database. I am trying to write some reports against this database. However, Access chokes when I write the select query of the report with SQL syntax specific to SQL Server that doesn't exist in access. Shouldn't this work, since it's the SQL Server engine running the queries and just sending the data back to Access to display? Is there any way to get this to work? Need this to work on any combination of Access 2007 and 2010, and SQL Server 2005 and 2008. Edit Note: I cannot create a SQL Server stored procedure or function, or otherwise modify the original (SQL Server) schema in any way.

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  • Am I missing something about LINQ?

    - by Jason Baker
    I seem to be missing something about LINQ. To me, it looks like it's taking some of the elements of SQL that I like the least and moving them into the C# language and using them for other things. I mean, I could see the benefit of using SQL-like statements on things other than databases. But if I wanted to write SQL, well, why not just write SQL and keep it out of C#? What am I missing here?

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  • LINQ for SQL Developers and DBA’s

    - by AtulThakor
    Firstly I’d just like to thank the guys who organise the SQL Server User Group (Martin/Tony/Chris) and for giving me the opportunity to speak at the recent event. Sorry about the slides taking so long but here they are along with some extra information. Firstly the demo’s were all done using LINQPad 4.0 which can be downloaded here: http://www.linqpad.net/ There are 2 versions 3.5/4.0 With 3.5 you should be able to replicate the problem I showed where a query using a parameter which is X characters long would create a different execution plan to a query which uses a parameter which is Y characters long, otherwise I would just use 4.0 The sample database used is AdventureWorksLT2008 which can be downloaded from here: http://msftdbprodsamples.codeplex.com/releases/view/37109 The scripts have been named so that you can select the appropriate way to run them i.e.: C# expression / C#statement, each script can be run individually be highlighting the query and clicking the play symbol or hitting F5. Scripts and Slides: http://sqlblogcasts.com/blogs/atulthakor/An%20Introduction%20to%20LINQ.zip Please don't hesitate in sending any questions via email/twitter, I’ll try my best to answer your questions! Thanks, Atul

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  • Need help limiting a join in Transact-sql

    - by MsLis
    I'm somewhat new to SQL and need help with query syntax. My issue involves 2 tables within a larger multi-table join under Transact-SQL (MS SQL Server 2000 Query Analyzer) I have ACCOUNTS and LOGINS, which are joined on 2 fields: Site & Subset. Both tables may have multiple rows for each Site/Subset combination. ACCOUNTS: | LOGINS: SITE SUBSET FIELD FIELD FIELD | SITE SUBSET USERID PASSWD alpha bravo blah blah blah | alpha bravo foo bar alpha charlie blah blah blah | alpha bravo bar foo alpha charlie bleh bleh blue | alpha charlie id ego delta bravo blah blah blah | delta bravo john welcome delta foxtrot blah blah blah | delta bravo jane welcome | delta bravo ken welcome | delta bravo barbara welcome I want to select all rows in ACCOUNTS which have LOGIN entries, but only 1 login per account. DESIRED RESULT: SITE SUBSET FIELD FIELD FIELD USERID PASSWD alpha bravo blah blah blah foo bar alpha charlie blah blah blah id ego alpha charlie bleh bleh blue id ego delta bravo blah blah blah jane welcome I don't really care which row from the login table I get, but the UserID and Password have to correspond. [Don't return invalid combinations like foo/foo or bar/bar] MS Access has a handy FIRST function, which can do this, but I haven't found an equivalent in TSQL. Also, if it makes a difference, other tables are joined to ACCOUNTS, but this is the only use of LOGINS in the structure. Thank you very much for any assistance.

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  • Schema objects not visible in SQL Server Management Studio 2008

    - by Germ
    I'm experiencing a weird problem with a SQL login. When I connect to the server in Microsoft SQL Server Management Studio (2008) using this account, I cannot see any of the tables, stored procedures etc. that this account should have access to on a particular database. When I connect to the same server within Visual Studio (2008) with the same account everything is there. When I connect with the same account on a Virtual Machine everything is there. I've also had a co-worker connect to the server using the same login and he's able to view everything as well. I use Microsoft SQL Server Management Studio all day connecting to different servers and databases and I've never experienced this problem. Does anyone have any suggestions on how I can diagnose this problem? I've checked to make sure I don't have any Table filters etc. There's several database on this server and I'm able to see the correct tables that this account has access to in the other databases just fine. Running this query lists the tables I'm expecting to see. SELECT * FROM INFORMATION_SCHEMA.TABLES

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  • Instantiate object from Linq to XML Query

    - by objectsbinding
    Hi All I have the following class public class CountrySpecificPIIEntity { public string Country { get; set; } public string CreditCardType { get; set; } public String Api { get; set; } public List<String> FilterList { get; set; } } I am trying to use a linq to XMl query to create a list of instances of type CountrySpecificPIIEntity. The XML is as below <piisettings> <country countrycode="DE"> <creditcardype credicardtype="mastercard"> <api api="INSERT_FILTERS"> <filters> <filter>FIRSTNAME</filter> <filter>HOUSENUMBER</filter> <filter>ADDITIONALADDRESSINFO</filter> <filter>EMAIL</filter> </filters> </api> </creditcardype> <creditcardype credicardtype="visa"> <api api="INSERT_FILTERS"> <filters> <filter>STATE</filter> <filter>EMAIL</filter> </filters> </api> </creditcardype> <creditcardype credicardtype="visa"> <api api="UPDATE_FILTERS"> <filters> <filter>STATE</filter> <filter>EMAIL</filter> </filters> </api> </creditcardype> </country> <country countrycode="GB"> <creditcardype credicardtype="americanexpress"> <api api="INSERT_FILTERS"> <filters> <filter>STREET</filter> <filter>ZIP</filter> <filter>CITY</filter> <filter>STATE</filter> <filter>EMAIL</filter> </filters> </api> </creditcardype> <creditcardype credicardtype="debank"> <api api="INSERT_FILTERS"> <filters> <filter>IPADDRESSCUSTOMER</filter> <filter>FIRSTNAME</filter> <filter>SURNAME</filter> <filter>HOUSENUMBER</filter> <filter>STREET</filter> <filter>ZIP</filter> <filter>CITY</filter> <filter>STATE</filter> <filter>EMAIL</filter> </filters> </api> </creditcardype> </country> </piisettings> what should the Linq to XML query be?

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  • Sql Server Compact 2005 on Visual Studio 2008

    - by Tim
    I'm working on a Windows Forms application that interacts with a Sql Compact database file created by SQL Server 2005. This application was originally developed in Visual Studio 2005 but was recently converted to a Visual Studio 2008 solution. In regards to Sql Compact, we made sure the references were all still set to the assemblies that handle the 2005 version of Sql Compact rather than Sql Compact 3.5. Having done this, the application still runs just as it should - it will still interact with the Compact database, perform synchronization operations, etc. However, I just discovered today that Visual Studio tools such as the DataSet Designer do not play well with a Sql Compact database file of an older version than 3.5. If I go to the New Connection... wizard, the only Sql Compact Data Source / Data Provider are for Sql Compact 3.5. I assume that Visual Studio 2008 just doesn't include the data provider for the older version of Sql Compact by default. Is there a way you can add the old version of Sql Compact to the list of "Data Sources" for the connection wizard? To see exactly what I'm referring to, click on the Tools menu of Visual Studio 2008 and click Connect to Database... In the window that comes up, click Change... next to the Data source setting. From this dialog there is no way I can select the earlier version of Sql Compact - only 3.5 is available. Maybe I need to add an assembly reference somewhere? Or copy some file(s) from my Visual Studio 2005 directory over to 2008? I would think there would have to be a way for Visual Studio 2008 to be able to interact with a Sql Compact database from Sql Server 2005. To provide one more bit of detail, I discovered this problem when I went to my DataSet, right-clicked and tried to add a TableAdapter. The first screen that comes up says, "Choose Your Data Connection". If I leave it set to the Sql Compact connection that we've always used, I now get the following error when clicking the Next button: Failed to open a connection to the database "The selected database was created with an earlier version of SQL Server Compact and needs to be upgraded to SQL Server Compact 3.5 before the connection can be opened or tested. Upgrade the database by creating a new data connection and completing the Add Connection dialog box." Check the connection and try again. The only problem here is that we still use Sql Server 2005, and if my understanding is correct, it does not produce subscription files that are compatible with Sql Compact 3.5. If I am wrong in this assumption, please correct me. Any help you can provide is greatly appreciated. Thank you.

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  • SQL Agent Logon - What is going on?

    - by James Wiseman
    I have a DTSX package that is called from a SQL Agent Job. The DTSX package references a file at a fixed location (e.g. e:\mssql\myfile.txt). On most machines, this location exists, but on some I have to manually map this (which is not a problem - I know a better solution would be to use package conifgurations to dynamically pull the file location, but this is not an option here - and anyway I'd like to understand what is going on) I have set up the agent service to run as a specific user (e.g. myuser) When I log on as this user and map the directory, then run the dtsx package directly, then all goes well. When I run the package through a SQL Agent Job, the file cannot be found. If I add a command line job step to the agent job to map the drive: net use e: \\svr\location Then all works file also. So what is going on in the backgound? How come the SQL Agent user requries the drive mapping even when I am logged in as this user.

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  • Write a sql for updating data based on time

    - by Lu Lu
    Hello everyone, Because I am new with SQL Server and T-SQL, so I will need your help. I have 2 table: Realtime and EOD. To understand my question, I give example data for 2 tables: ---Realtime table--- Symbol Date Value ABC 1/3/2009 03:05:01 327 // this day is not existed in EOD -> inserting BBC 1/3/2009 03:05:01 458 // this day is not existed in EOD -> inserting ABC 1/2/2009 03:05:01 326 // this day is new -> updating BBC 1/2/2009 03:05:01 454 // this day is new -> updating ABC 1/2/2009 02:05:01 323 BBC 1/2/2009 02:05:01 453 ABC 1/2/2009 01:05:01 313 BBC 1/2/2009 01:05:01 423 ---EOD table--- Symbol Date Value ABC 1/2/2009 02:05:01 323 BBC 1/2/2009 02:05:01 453 I will need to create a store procedure to update value of symbols. If data in day of a symbol is new (compare between Realtime & EOD), it will update value and date for EOD at that day if existing, otherwise inserting. And store will update EOD table with new data: ---EOD table--- Symbol Date Value ABC 1/3/2009 03:05:01 327 BBC 1/3/2009 03:05:01 458 ABC 1/2/2009 03:05:01 326 BBC 1/2/2009 03:05:01 454 P/S: I use SQL Server 2005. And I have a similar answered question at here: http://stackoverflow.com/questions/2726369/help-to-the-way-to-write-a-query-for-the-requirement Please help me. Thanks.

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  • Return type from DAL class (Sql ce, Linq to Sql)

    - by bretddog
    Hi, Using VS2008 and Sql CE 3.5, and preferably Linq to Sql. I'm learning database, and unsure about DAL methods return types and how/where to map the data over to my business objects: I don't want direct UI binding. A business object class UserData, and a class UserDataList (Inherits List(Of UserData)), is represented in the database by the table "Users". I use SQL Compact and run SqlMetal which creates dbml/designer.vb file. This gives me a class with a TableAttribute: <Table()> _ Partial Public Class Users I'm unsure how to use this class. Should my business object know about this class, such that the DAL can return the type Users, or List(Of Users) ? So for example the "UserDataService Class" is a part of the DAL, and would have for example the functions GetAll and GetById. Will this be correct : ? Public Class UserDataService Public Function GetAll() As List(Of Users) Dim ctx As New MyDB(connection) Dim q As List(Of Users) = From n In ctx.Users Select n Return q End Function Public Function GetById(ByVal id As Integer) As Users Dim ctx As New MyDB(connection) Dim q As Users = (From n In ctx.Users Where n.UserID = id Select n).Single Return q End Function And then, would I perhaps have a method, say in the UserDataList class, like: Public Class UserDataList Inherits List(Of UserData) Public Sub LoadFromDatabase() Me.clear() Dim database as New UserDataService dim users as List(Of Users) users = database.GetAll() For each u in users dim newUser as new UserData newUser.Id = u.Id newUser.Name = u.Name Me.Add(newUser) Next End Sub End Class Is this a sensible approach? Would appreciate any suggestions/alternatives, as this is my first attempt on a database DAL. cheers!

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  • Update SQL Server 2000 to SQL Server 2008: Benefits please?

    - by Ciaran Archer
    Hi there I'm looking for the benefits of upgrading from SQL Server 2000 to 2008. I was wondering: What database features can we leverage with 2008 that we can't now? What new TSQL features can we look forward to using? What performance benefits can we expect to see? What else will make management go for it? And the converse: What problems can we expect to encounter? What other problems have people found when migrating? Why fix something that isn't (technically) broken? We work in a Java shop, so any .NET / CLR stuff won't rock our world. We also use Eclipse as our main development so any integration with Visual Studio won't be a plus. We do use SQL Server Management Studio however. Some background: Our main database machine is a 32bit Dell Intel Xeon MP CPU 2.0GHz, 40MB of RAM with Physical Address Extension running Windows Server 2003 Enterprise Edition. We will not be changing our hardware. Our databases in total are under a TB with some having more than 200 tables. But they are busy and during busy times we see 60-80% CPU utilisation. Apart form the fact that SQL Server 2000 is coming close to end of life, why should we upgrade? Any and all contributions are appreciated!

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  • Strange Sql Server 2005 behavior

    - by Justin C
    Background: I have a site built in ASP.NET with Sql Server 2005 as it's database. The site is the only site on a Windows Server 2003 box sitting in my clients server room. The client is a local school district, so for data security reasons there is no remote desktop access and no remote Sql Server connection, so if I have to service the database I have to be at the terminal. I do have FTP access to update ASP code. Problem: I was contacted yesterday about an issue with the system. When I looked in to it, it seems a bug that I had solved nearly a year ago had returned. I have a stored procedure that used to take an int as a parameter but a year ago we changed the structure of the system and updated the stored procedure to take an nvarchar(10). The stored procedure somehow changed back to taking an int instead of an nvarchar. There is an external hard drive connected to the server that copies data periodically and has the ability to restore the server in case of failure. I would have assumed that somehow an older version of the database had been restored, but data that I know was inserted 7 days and 1 day before the bug occurred is still in the database. Question: Is there anyway that the structure of a Sql Server 2005 database can revert to a previous version or be restored to a previous version without touching the actual data? No one else should have access to the server so I'm going a little insane trying to figure out how this even happened. Any ideas?

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  • Creating reusable chunks of Linq to SQL

    - by tia
    Hi, I am trying to break up horrible linq to sql queries to make them a bit more readable. Say I want to return all orders for product which in the previous year had more than 100 orders. So, original query is: from o in _context.Orders where (from o1 in _context.Orders where o1.Year == o.Year - 1 && o1.Product == o.Product select o1).Count() > 100 select o; Messy. What I'd like to be able to do is to be able to break it down, eg: private IEnumerable<Order> LastSeasonOrders(Order order) { return (from o in _context.Orders where o.Year == order.Year - 1 && o.Product == order.Product select o); } which then lets me change the original query to: from o in _context.Orders where LastSeasonOrders(o).Count() > 100 select o; This doesn't seem to work, as I get method Blah has no supported translation to SQL when the query is run. Any quick tips on the correct way to achieve this?

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  • Why is the use of abstractions (such as LINQ) so taboo?

    - by Matthew Patrick Cashatt
    I am an independent contractor and, as such, I interview 3-4 times a year for new gigs. I am in the midst of that cycle now and got turned down for an opportunity even though I felt like the interview went well. The same thing has happened to me a couple of times this year. Now, I am not a perfect guy and I don't expect to be a good fit for every organization. That said, my batting average is lower than usual so I politely asked my last interviewer for some constructive feedback, and he delivered! The main thing, according to the interviewer, was that I seemed to lean too much towards the use of abstractions (such as LINQ) rather than towards lower-level, organically grown algorithms. On the surface, this makes sense--in fact, it made the other rejections make sense too because I blabbed about LINQ in those interviews as well and it didn't seem that the interviewers knew much about LINQ (even though they were .NET guys). So now I am left with this question: If we are supposed to be "standing on the shoulders of giants" and using abstractions that are available to us (like LINQ), then why do some folks consider it so taboo? Doesn't it make sense to pull code "off the shelf" if it accomplishes the same goals without extra cost? It would seem to me that LINQ, even if it is an abstraction, is simply an abstraction of all the same algorithms one would write to accomplish exactly the same end. Only a performance test could tell you if your custom approach was better, but if something like LINQ met the requirements, why bother writing your own classes in the first place? I don't mean to focus on LINQ here. I am sure that the JAVA world has something comparable, I just would like to know why some folks get so uncomfortable with the idea of using an abstraction that they themselves did not write. UPDATE As Euphoric pointed out, there isn't anything comparable to LINQ in the Java world. So, if you are developing on the .NET stack, why not always try and make use of it? Is it possible that people just don't fully understand what it does?

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  • Are there any good resources for refactoring existing C# code to use LINQ while keeping your tests passing?

    - by Paddyslacker
    I've been teaching myself a little LINQ and an exercise I thought would be useful was to take my existing Project Euler C# code, which I built using Test Driven Development and gradually convert it to LINQ. I realise that LINQ is not always the best solution for all of the Project Euler problems, but I don't want to get into that here. I'm wondering whether or not it's feasible to refactor "traditional" OO C# code to use LINQ and functional programming syntax whilst keeping all of your tests passing. I can't find a way to make the tiny steps I'm used to making using TDD when converting to LINQ and this is a roadblock for me. I seem to have to make large changes to come up with a single function that I then replace whole chunks of my code with. I realise I could write this from scratch in LINQ, but in the real world, I'd like to be able to replace parts of my existing C# code to take advantage of LINQ where appropriate. Has anyone been successful with this approach? What resources did you find useful for refactoring existing C# code to use LINQ whilst taking a Test Driven Development approach?

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  • Basic Spatial Data with SQL Server and Entity Framework 5.0

    - by Rick Strahl
    In my most recent project we needed to do a bit of geo-spatial referencing. While spatial features have been in SQL Server for a while using those features inside of .NET applications hasn't been as straight forward as could be, because .NET natively doesn't support spatial types. There are workarounds for this with a few custom project like SharpMap or a hack using the Sql Server specific Geo types found in the Microsoft.SqlTypes assembly that ships with SQL server. While these approaches work for manipulating spatial data from .NET code, they didn't work with database access if you're using Entity Framework. Other ORM vendors have been rolling their own versions of spatial integration. In Entity Framework 5.0 running on .NET 4.5 the Microsoft ORM finally adds support for spatial types as well. In this post I'll describe basic geography features that deal with single location and distance calculations which is probably the most common usage scenario. SQL Server Transact-SQL Syntax for Spatial Data Before we look at how things work with Entity framework, lets take a look at how SQL Server allows you to use spatial data to get an understanding of the underlying semantics. The following SQL examples should work with SQL 2008 and forward. Let's start by creating a test table that includes a Geography field and also a pair of Long/Lat fields that demonstrate how you can work with the geography functions even if you don't have geography/geometry fields in the database. Here's the CREATE command:CREATE TABLE [dbo].[Geo]( [id] [int] IDENTITY(1,1) NOT NULL, [Location] [geography] NULL, [Long] [float] NOT NULL, [Lat] [float] NOT NULL ) Now using plain SQL you can insert data into the table using geography::STGeoFromText SQL CLR function:insert into Geo( Location , long, lat ) values ( geography::STGeomFromText ('POINT(-121.527200 45.712113)', 4326), -121.527200, 45.712113 ) insert into Geo( Location , long, lat ) values ( geography::STGeomFromText ('POINT(-121.517265 45.714240)', 4326), -121.517265, 45.714240 ) insert into Geo( Location , long, lat ) values ( geography::STGeomFromText ('POINT(-121.511536 45.714825)', 4326), -121.511536, 45.714825) The STGeomFromText function accepts a string that points to a geometric item (a point here but can also be a line or path or polygon and many others). You also need to provide an SRID (Spatial Reference System Identifier) which is an integer value that determines the rules for how geography/geometry values are calculated and returned. For mapping/distance functionality you typically want to use 4326 as this is the format used by most mapping software and geo-location libraries like Google and Bing. The spatial data in the Location field is stored in binary format which looks something like this: Once the location data is in the database you can query the data and do simple distance computations very easily. For example to calculate the distance of each of the values in the database to another spatial point is very easy to calculate. Distance calculations compare two points in space using a direct line calculation. For our example I'll compare a new point to all the points in the database. Using the Location field the SQL looks like this:-- create a source point DECLARE @s geography SET @s = geography:: STGeomFromText('POINT(-121.527200 45.712113)' , 4326); --- return the ids select ID, Location as Geo , Location .ToString() as Point , @s.STDistance( Location) as distance from Geo order by distance The code defines a new point which is the base point to compare each of the values to. You can also compare values from the database directly, but typically you'll want to match a location to another location and determine the difference for which you can use the geography::STDistance function. This query produces the following output: The STDistance function returns the straight line distance between the passed in point and the point in the database field. The result for SRID 4326 is always in meters. Notice that the first value passed was the same point so the difference is 0. The other two points are two points here in town in Hood River a little ways away - 808 and 1256 meters respectively. Notice also that you can order the result by the resulting distance, which effectively gives you results that are ordered radially out from closer to further away. This is great for searches of points of interest near a central location (YOU typically!). These geolocation functions are also available to you if you don't use the Geography/Geometry types, but plain float values. It's a little more work, as each point has to be created in the query using the string syntax, but the following code doesn't use a geography field but produces the same result as the previous query.--- using float fields select ID, geography::STGeomFromText ('POINT(' + STR (long, 15,7 ) + ' ' + Str(lat ,15, 7) + ')' , 4326), geography::STGeomFromText ('POINT(' + STR (long, 15,7 ) + ' ' + Str(lat ,15, 7) + ')' , 4326). ToString(), @s.STDistance( geography::STGeomFromText ('POINT(' + STR(long ,15, 7) + ' ' + Str(lat ,15, 7) + ')' , 4326)) as distance from geo order by distance Spatial Data in the Entity Framework Prior to Entity Framework 5.0 on .NET 4.5 consuming of the data above required using stored procedures or raw SQL commands to access the spatial data. In Entity Framework 5 however, Microsoft introduced the new DbGeometry and DbGeography types. These immutable location types provide a bunch of functionality for manipulating spatial points using geometry functions which in turn can be used to do common spatial queries like I described in the SQL syntax above. The DbGeography/DbGeometry types are immutable, meaning that you can't write to them once they've been created. They are a bit odd in that you need to use factory methods in order to instantiate them - they have no constructor() and you can't assign to properties like Latitude and Longitude. Creating a Model with Spatial Data Let's start by creating a simple Entity Framework model that includes a Location property of type DbGeography: public class GeoLocationContext : DbContext { public DbSet<GeoLocation> Locations { get; set; } } public class GeoLocation { public int Id { get; set; } public DbGeography Location { get; set; } public string Address { get; set; } } That's all there's to it. When you run this now against SQL Server, you get a Geography field for the Location property, which looks the same as the Location field in the SQL examples earlier. Adding Spatial Data to the Database Next let's add some data to the table that includes some latitude and longitude data. An easy way to find lat/long locations is to use Google Maps to pinpoint your location, then right click and click on What's Here. Click on the green marker to get the GPS coordinates. To add the actual geolocation data create an instance of the GeoLocation type and use the DbGeography.PointFromText() factory method to create a new point to assign to the Location property:[TestMethod] public void AddLocationsToDataBase() { var context = new GeoLocationContext(); // remove all context.Locations.ToList().ForEach( loc => context.Locations.Remove(loc)); context.SaveChanges(); var location = new GeoLocation() { // Create a point using native DbGeography Factory method Location = DbGeography.PointFromText( string.Format("POINT({0} {1})", -121.527200,45.712113) ,4326), Address = "301 15th Street, Hood River" }; context.Locations.Add(location); location = new GeoLocation() { Location = CreatePoint(45.714240, -121.517265), Address = "The Hatchery, Bingen" }; context.Locations.Add(location); location = new GeoLocation() { // Create a point using a helper function (lat/long) Location = CreatePoint(45.708457, -121.514432), Address = "Kaze Sushi, Hood River" }; context.Locations.Add(location); location = new GeoLocation() { Location = CreatePoint(45.722780, -120.209227), Address = "Arlington, OR" }; context.Locations.Add(location); context.SaveChanges(); } As promised, a DbGeography object has to be created with one of the static factory methods provided on the type as the Location.Longitude and Location.Latitude properties are read only. Here I'm using PointFromText() which uses a "Well Known Text" format to specify spatial data. In the first example I'm specifying to create a Point from a longitude and latitude value, using an SRID of 4326 (just like earlier in the SQL examples). You'll probably want to create a helper method to make the creation of Points easier to avoid that string format and instead just pass in a couple of double values. Here's my helper called CreatePoint that's used for all but the first point creation in the sample above:public static DbGeography CreatePoint(double latitude, double longitude) { var text = string.Format(CultureInfo.InvariantCulture.NumberFormat, "POINT({0} {1})", longitude, latitude); // 4326 is most common coordinate system used by GPS/Maps return DbGeography.PointFromText(text, 4326); } Using the helper the syntax becomes a bit cleaner, requiring only a latitude and longitude respectively. Note that my method intentionally swaps the parameters around because Latitude and Longitude is the common format I've seen with mapping libraries (especially Google Mapping/Geolocation APIs with their LatLng type). When the context is changed the data is written into the database using the SQL Geography type which looks the same as in the earlier SQL examples shown. Querying Once you have some location data in the database it's now super easy to query the data and find out the distance between locations. A common query is to ask for a number of locations that are near a fixed point - typically your current location and order it by distance. Using LINQ to Entities a query like this is easy to construct:[TestMethod] public void QueryLocationsTest() { var sourcePoint = CreatePoint(45.712113, -121.527200); var context = new GeoLocationContext(); // find any locations within 5 kilometers ordered by distance var matches = context.Locations .Where(loc => loc.Location.Distance(sourcePoint) < 5000) .OrderBy( loc=> loc.Location.Distance(sourcePoint) ) .Select( loc=> new { Address = loc.Address, Distance = loc.Location.Distance(sourcePoint) }); Assert.IsTrue(matches.Count() > 0); foreach (var location in matches) { Console.WriteLine("{0} ({1:n0} meters)", location.Address, location.Distance); } } This example produces: 301 15th Street, Hood River (0 meters)The Hatchery, Bingen (809 meters)Kaze Sushi, Hood River (1,074 meters)   The first point in the database is the same as my source point I'm comparing against so the distance is 0. The other two are within the 5 mile radius, while the Arlington location which is 65 miles or so out is not returned. The result is ordered by distance from closest to furthest away. In the code, I first create a source point that is the basis for comparison. The LINQ query then selects all locations that are within 5km of the source point using the Location.Distance() function, which takes a source point as a parameter. You can either use a pre-defined value as I'm doing here, or compare against another database DbGeography property (say when you have to points in the same database for things like routes). What's nice about this query syntax is that it's very clean and easy to read and understand. You can calculate the distance and also easily order by the distance to provide a result that shows locations from closest to furthest away which is a common scenario for any application that places a user in the context of several locations. It's now super easy to accomplish this. Meters vs. Miles As with the SQL Server functions, the Distance() method returns data in meters, so if you need to work with miles or feet you need to do some conversion. Here are a couple of helpers that might be useful (can be found in GeoUtils.cs of the sample project):/// <summary> /// Convert meters to miles /// </summary> /// <param name="meters"></param> /// <returns></returns> public static double MetersToMiles(double? meters) { if (meters == null) return 0F; return meters.Value * 0.000621371192; } /// <summary> /// Convert miles to meters /// </summary> /// <param name="miles"></param> /// <returns></returns> public static double MilesToMeters(double? miles) { if (miles == null) return 0; return miles.Value * 1609.344; } Using these two helpers you can query on miles like this:[TestMethod] public void QueryLocationsMilesTest() { var sourcePoint = CreatePoint(45.712113, -121.527200); var context = new GeoLocationContext(); // find any locations within 5 miles ordered by distance var fiveMiles = GeoUtils.MilesToMeters(5); var matches = context.Locations .Where(loc => loc.Location.Distance(sourcePoint) <= fiveMiles) .OrderBy(loc => loc.Location.Distance(sourcePoint)) .Select(loc => new { Address = loc.Address, Distance = loc.Location.Distance(sourcePoint) }); Assert.IsTrue(matches.Count() > 0); foreach (var location in matches) { Console.WriteLine("{0} ({1:n1} miles)", location.Address, GeoUtils.MetersToMiles(location.Distance)); } } which produces: 301 15th Street, Hood River (0.0 miles)The Hatchery, Bingen (0.5 miles)Kaze Sushi, Hood River (0.7 miles) Nice 'n simple. .NET 4.5 Only Note that DbGeography and DbGeometry are exclusive to Entity Framework 5.0 (not 4.4 which ships in the same NuGet package or installer) and requires .NET 4.5. That's because the new DbGeometry and DbGeography (and related) types are defined in the 4.5 version of System.Data.Entity which is a CLR assembly and is only updated by major versions of .NET. Why this decision was made to add these types to System.Data.Entity rather than to the frequently updated EntityFramework assembly that would have possibly made this work in .NET 4.0 is beyond me, especially given that there are no native .NET framework spatial types to begin with. I find it also odd that there is no native CLR spatial type. The DbGeography and DbGeometry types are specific to Entity Framework and live on those assemblies. They will also work for general purpose, non-database spatial data manipulation, but then you are forced into having a dependency on System.Data.Entity, which seems a bit silly. There's also a System.Spatial assembly that's apparently part of WCF Data Services which in turn don't work with Entity framework. Another example of multiple teams at Microsoft not communicating and implementing the same functionality (differently) in several different places. Perplexed as a I may be, for EF specific code the Entity framework specific types are easy to use and work well. Working with pre-.NET 4.5 Entity Framework and Spatial Data If you can't go to .NET 4.5 just yet you can also still use spatial features in Entity Framework, but it's a lot more work as you can't use the DbContext directly to manipulate the location data. You can still run raw SQL statements to write data into the database and retrieve results using the same TSQL syntax I showed earlier using Context.Database.ExecuteSqlCommand(). Here's code that you can use to add location data into the database:[TestMethod] public void RawSqlEfAddTest() { string sqlFormat = @"insert into GeoLocations( Location, Address) values ( geography::STGeomFromText('POINT({0} {1})', 4326),@p0 )"; var sql = string.Format(sqlFormat,-121.527200, 45.712113); Console.WriteLine(sql); var context = new GeoLocationContext(); Assert.IsTrue(context.Database.ExecuteSqlCommand(sql,"301 N. 15th Street") > 0); } Here I'm using the STGeomFromText() function to add the location data. Note that I'm using string.Format here, which usually would be a bad practice but is required here. I was unable to use ExecuteSqlCommand() and its named parameter syntax as the longitude and latitude parameters are embedded into a string. Rest assured it's required as the following does not work:string sqlFormat = @"insert into GeoLocations( Location, Address) values ( geography::STGeomFromText('POINT(@p0 @p1)', 4326),@p2 )";context.Database.ExecuteSqlCommand(sql, -121.527200, 45.712113, "301 N. 15th Street") Explicitly assigning the point value with string.format works however. There are a number of ways to query location data. You can't get the location data directly, but you can retrieve the point string (which can then be parsed to get Latitude and Longitude) and you can return calculated values like distance. Here's an example of how to retrieve some geo data into a resultset using EF's and SqlQuery method:[TestMethod] public void RawSqlEfQueryTest() { var sqlFormat = @" DECLARE @s geography SET @s = geography:: STGeomFromText('POINT({0} {1})' , 4326); SELECT Address, Location.ToString() as GeoString, @s.STDistance( Location) as Distance FROM GeoLocations ORDER BY Distance"; var sql = string.Format(sqlFormat, -121.527200, 45.712113); var context = new GeoLocationContext(); var locations = context.Database.SqlQuery<ResultData>(sql); Assert.IsTrue(locations.Count() > 0); foreach (var location in locations) { Console.WriteLine(location.Address + " " + location.GeoString + " " + location.Distance); } } public class ResultData { public string GeoString { get; set; } public double Distance { get; set; } public string Address { get; set; } } Hopefully you don't have to resort to this approach as it's fairly limited. Using the new DbGeography/DbGeometry types makes this sort of thing so much easier. When I had to use code like this before I typically ended up retrieving data pks only and then running another query with just the PKs to retrieve the actual underlying DbContext entities. This was very inefficient and tedious but it did work. Summary For the current project I'm working on we actually made the switch to .NET 4.5 purely for the spatial features in EF 5.0. This app heavily relies on spatial queries and it was worth taking a chance with pre-release code to get this ease of integration as opposed to manually falling back to stored procedures or raw SQL string queries to return spatial specific queries. Using native Entity Framework code makes life a lot easier than the alternatives. It might be a late addition to Entity Framework, but it sure makes location calculations and storage easy. Where do you want to go today? ;-) Resources Download Sample Project© Rick Strahl, West Wind Technologies, 2005-2012Posted in ADO.NET  Sql Server  .NET   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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    - by Edward Boyle
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