Simplify LINQ-To-Entity Query, And Make It Dynamic
Dec 4, 2010
I have this query for getting data through Entity Framework, which works today. Thing is, i want to create the query dynamically, i.e build it up in blocks, but i can't figure out how exactly to do it. I believe if i can somehow save one of the values that i retrieve in the beginning i can do it, but now i retrieve it twice (probably a bit slow as well? Unless the compiler fixes it before quering). Makes sense? Here is the LINQ:
is it possible to make a Linq query dynamic in the following pseduo code (to show what I'm trying to do)
[Code]....
where a2 and a3 and a4 are being populated from user controls and only one will apply. So query is done by state, zip or by city, but not by more than one, so the other two would be null. So the operator is really "OR" but I haven't found anything on a "or" or "whereOr" operator.
simplify the look of buttons,layouts son we can simplify the look of a site for smartphone?The idea is to represent links instead of buttons and to replace any loyout to just the left in order to be better viewable in a smartphone,
string strCondition = "FirstName=='abc'" from p in People.Where(strCondition) select p
In our architecture we are usign both Linq-Sql as well Linq-Entity. So please give some thoughts wehter it is possible or not and is there any way to perform this?
Hi guys I need to rewrite the sql query below using Linq to entity. Unfortunately I don't have a lot of experience of using Linq.
With TempTableName AS (SELECT [ColumnName], [ColumnName2], [ColumnName3], [ColumnName4], ROW_NUMBER() OVER (order by ColumnName desc) as RowNumber from TableName ) SELECT [ColumnName], [ColumnName2], [ColumnName3], [ColumnName4] FROM TempTableName WHERE ROWNUMBER Between 10 and 100
I have a web app for our golf club. When I compute handicap index for each golfer, I have to select the most recent scores and then a subset of those scores depending on how many rounds of golf the golfer has played. All the scores are entered into a single SQL Express table called "Rounds". Verbally, this is what I'm trying to do:
1) select the twenty most recent golf scores (sort on date descending, "take(20)") [if less than 20 records, then select all available];
2) for this set of records, select the 10 lowest scores (or smaller number if golfer has less than 20 rounds);
3) compute the average round differential for the subset of records, etc. to calculate handicap index (this step is working ok...)
My current VB code has this LINQ query (which is flawed -- it selects the lowest handicap differential scores of ALL records for the filtered user):
[Code]....
How do I modify this query to accomplish items 1) & 2) above? It seems this should be simple, but my experience with queries is still limited.
Need to figure out the correct way to do a simple SUM function in Linq, but also manipulate one of the feilds coming back by doing a Substring on it, here is the original SQL query:
I am having a meltdown over something that seems so simple and yet isn't working. Here's my scenario.
I have an object structure of tEvents, which contains properties of an event like a run of concerts. tEvents in turn contains an entity set of tEventOptions, which include properties like EventDate, Cancelled etc. I would like to query a list of tEvents using properties of the tEventOptions, for example filtering by date.
My pageis using a calendar object to show event dates. So I am trying to find if any tEvents in the List coming back from the database match the date of the day element being rendered in my Calendar control like so (in this snip 'data' is List and results from a db query):
[code]....
Except r, my query result var, is always true no matter what data it receives. I have tried the sub query using other properties of tEventOption and get the same 'true' result each time. I know that the data does not reflect this result so I clearly have a problem with the structure of my query, but for the life of me I cannot find a way to resolve it.
Best way to show the SQL trace of a LINQ query to Entity Framework 3.5? I am using ASP.net and EF 3.5.
Dim dbo As Web.Portal.RBMEntities = New Web.Portal.RBMEntities Dim Query = From RoleAllocations In dbo.RoleAllocations Where RoleAllocations.user_id = _ID And RoleAllocations.expire_date > Today Select RoleAllocations
I am new to this, and I am trying to implement a linq query similar to db.Genres.Include("Albums") command from
mvc music store using my current DB setup. I realize that the tutorial mentions Checlking the "Include foreign key columns in the method" when creating the tables in ADO.NET, but if I am using LINQ to SQL classes, then how can I obtain the same effect. And how do I use db.Genres.Include("Albums") to simplify my life?
I have a table created on the fly. The table structure is dynamic.
This is the table structure generated by the end of year 2010
DealerCode, 201010, 201011, 201012
This is the table structure generated by the end of Jan 2011
DealerCode, 201011, 201012, 201101
What I need to do is selecting all data and then bind it into a gridview
To build a LINQ query, we need to drag the table into dbml file first. As we don't know how the table look like, can we add it in dynamically? Are there any other solutions?
I am writing a function in which i generate autocode in specific format i want to make this function generalize so that i send tablename and columnname parameter and function return the next code. I am using linq to sql with MVC e.g. i want to make table name and column name dyanamic
I was use SQL Connection to Access Data Base in Past and When Select Data in DataSet make it static & than it can avaliable on class level.I click on Edit Button its avalibale because its Static.Than now i think try it with LINQ it's provide easy Access to Data Base; in Insert/Update/Delete than SQL Connection it look's me great when i use it.
But i don't know how to make var Query Static for its class level avaliability. i can define it by my code
public static DataSet DsCustomers; protected void Page_Load(object sender, EventArgs e)[code]....
in LINQ example i want to make sure that SelectQuery is avaliable on Class level & want to make it static
I have a page with filters and accordingly to what the user selects, it has to generate a query. I'm using this code:
[code]....
However Linq-To-Sharepoint doesn't convert most of this to CAML and the list I'm querying has more than 50000 items. It takes about 4-8 seconds to retrieve the items which is not acceptable.
I've been trying to generate a dynamic query but so far I haven't been able to get it to work.
With AND and OR operations to generate the query I could put all those conditions on code and increase performance.
I have two text boxes for the user to enter UserName & First Name, both these fields are optional and not mandatory to fill.
once the user presses the Search button, i execute the following query to fetch matching records.
[Code]....
The problem is, in cases where User leaves both the textbox or one of the textbox empty/blank, in that case that particular field should be removed from where clause.
More like if something is entered then search for that particular record otherwise search for all the records.
The gist of the problem is that we have an alumni table (one record per person) and also a couple of other tables (one to many) that have degree info and interest info. In a search screen in our app you can search for criteria that spans all three tables (there are actually more fields and tables than shown in the example below but I am trying to keep it simple).
The code below works (properly returns people without degrees for example) but still feels a little clunky or over-engineered to me. Are there easier ways to do this? NOTE: I have been through quite a few iterations/approaches to making the correct data be returned.
Dim MediaQuery = From m In dB.DOWNLOADS _Where m.ID = id _Select
which returns a record from the database. One of the fields in the record is a FK to another table. I need to read this value to be able to set a dropdown based on the ID but I can't work out how to access it. For a standard record I can just do the following txtTitle.Text = MediaQuery.FirstOrDefault().TITLE
However with the foreign key it doesn't work like that. I've tried drpGroup.SelectedIndex = MediaQuery.FirstOrDefault().DOWNLOAD_GROUPS.ID where DOWNLOAD_GROUPS is the FK field but it returns Object reference not set to an instance of an object. If you're simply wanting to read some values from a single db record in the entitiy framework and one is a foreign key how should I go about getting the value?
1. I have a GridView on my page and it uses sqldatasource with parameterized query. What I want to do is, on page load (where nothing has been selected so no parameter supplied), I want it to query everything (something like SELECT * FROM [this_table]) but since my SelectCommand is something like
SELECT * FROM [this_table] WHERE [this_column] = @someParameters AND [that_column] = @someParameters.
Can I play around with default value to achieve something like that but how ? Now, when the page loads, it doesn't show anything (No Gridview).
2. On my page, I made something like (username, gender, address, and more) and one single search button. That means, no single control enable auto postback. What I am trying to accomplish is building dynamic query
(if username specifed -> SELECT * FROM [this_table] WHERE [username] LIKE @username).
If both username and gender are specified (SELECT * FROM [this_table] WHERE [username] LIKE @username AND [gender] = @gender) and you know the rest. How can I do this using GridView and SqlDataSource ? To my knowledge, I can only specify one SELECT statement in a sqldatasource.
I've build a linq query.But i want a random selection so its not always ID : 1,2,3,4,5,6 How can i randomize this var? I like to bind it to a repeater.//TagCloud:
Random rand = new Random(); var tc1 = from i in JumpTide.cms.menu.GetMenuItems(32) select new
