C# - Access Different Columns From LINQ Resultset?
Feb 26, 2011
I have a query which returns multiple columns from the database using LINQ
var donors = from d2 in db.Donors
where d2.Status == "Pending"
select new { donorID = d2.donorID, bloodGroup = d2.bloodGroup, contactNo = d2.contactMobile, status = d2.Status };
now I want to display the results in different Labels accessing one column value from donors resultset.
ex:
Label1.Text = donorID;
Label2.Text = bloodGroup; ...and so on
I have a situation where I am accessing a database multiple times and I'm wondering if it is necessary.
I have a GridView with a template column with a hyperlink to "Get Results" and on the RowDataBound event I have it check the batch number against the database and see if results exist and then if they don't, hide the link.
So when viewing the page if there is 20 rows in the gridview it is effectively doing 20 queries.
I was wondering if it is a better idea to query the database once with all "batches" and load it into a datatable, then on the RowDataBound event query the datatable. The only issue I see with this is there is currently 40,000 batches and grows daily.
I hava a textbox and button in my project. I want the button on click to add a new column inside the database "Trial.mdb" , table name "table1". The column name will be text typed in the textbox and it will be text type. How could I do that? with a sql code in asp:accessdatasource or in my code behind ?
I have a partitioned db where several tables have the exact same structure. I'm able to query the tables using linq, but only by quering the individual tables 1 at a time and by using the explicit table name. For example at the moment, I have 8 tables so I have something similar to the following:
[Code]....
Is there any way, that based on a certain value (stringValue), I could determine which table to query and then code the linq query just once?
Entity ID (PK), int Name Descrip Users ID (PK) EntityID, int (this is not connected to Entity table)
Now I am using LINQ to pull the records which has a Entity.ID = something. Which will show me couple of records in my GridView. Here is my LINQ statement:
protected void Page_Load(object sender, EventArgs e) { string getEntity = Request.QueryString["EntityID"]; int getIntEntity = Int32.Parse(getEntity); OISEntityTestingDataContext db = new OISEntityTestingDataContext(); //OISLinqtoSQLDataContext db = new OISLinqtoSQLDataContext(); var tr = from r in db.Users join s in db.Entities on r.UserID equals s.ID where s.ID == getIntEntity select new { //To Show Items in GridView! }; GridView1.DataSource = tr; GridView1.DataBind(); }
Now here I am getting an error mesg on 'join' The type of one of the expressions in the join clause is incorrect. Type inference failed in the call to 'Join What does that mean?
I have two tables.[Table.Game] Columns are "PK_id" "username" and "couponID" [Table.Coupons] Columns are "PK_id" "CouponID" and "Points" The two columns "CouponID" are associated with eachother. Let say i have two rows with the user "harry" in [Table.Game] this person has two different couponID. In [Table.Coupons] this user "harry" has "CouponID" 1 and 2. Column "Points" have 10 and 20. To the question how do u sum this two different point values that have different "CouponIDs". This does work if i have only one "CouponId". But not when the user has 2 different CouponIDs. Values is 0
var points = (from p in linq.Coupons join g in linq.games on p.couponID equals g.couponID where g.username == username && g.couponID == p.couponID select (int)p.win).Sum();
There may be a lot of data in the Blogs table. What if all I wanted was say BlogID, BlogTitle and BlogAuthor and nothing else, is there a way to do this in an effort to make the sql more efficent?
Along the same lines in my DataContext (.dbml) file I added some associations between some of my tables. This makes coding nice when I do a linq statement that will join those tables automatically for me but my concern is does it do that everytime, thus making all my linq quieries inefficient?
I have just started using LINQ with VS2008. I have added extra columns to my table, saved the changes, but class ClassName.Designer.CS didn't get updated. What do I have to do to updated the class? Do I have to do it manually, or is there a way to automatically synchronize tables and ClassName.Designer.CS?
I am using dynamic data entities linq to sql project. For my test project I have one table, with 10 columns and a single primary key for example. Almost all the columns are varchars.I can get the basic project up and running fine - update, delete, insert etc.ince it has no foreign keys, there are no search filters rendered. I was wondering if there was an easy way to generate a set of filters for the columns for this table. So a First name and last name search box. Is there a way to generate these filters for chosen columns and is there a way to generate these for all the columns
for example, above each of the columns in the grid there might be a text box ( I am not too fussed where the text boxes are rendered as such). Each of the text boxes will act as a filter for that column (doing a SQL 'like')
Initially, I wrote the GetTeamMember() method to display the FullName in the ItemTemplate.
Then as I wrote the EditTemplate, I needed to populate a DropDownList with a list of names (first and last). It was fairly easy using the LinqDataSource, however it currently only shows the LastName. I could write another method GetTeamMembers() to populate the ddlTeamMember with the data I want, but I thought maybe there's a better "LINQ" way.
So I'm looking for a better way to get FullName (i.e. Firstname + " " + LastName) into both lblTeamMember and ddlTeamMember.
Options I thought of are:
I could write a method GetTeamMembers() I write a StoredProc that returns the extra column Better way?
I need to know how to display the result of a select query in a datagrid or GridView with VB.NET?
Consider SELECT * FROM some_table. I don't know what columns the table has. Is there a way to just output the result to a table, with a dataset for example?
Can we use different resultset in our Report. Like if we have written two select statement in our SP, how can we use the different result set to bind them in our Report.
i want to get first picture of any album in photo table. i want get output table for show to the datalist control.i need to get albumid in output
so i create a sproc similar this:
create PROC USP_GETFirstPhoto @ALBUMID INT OUTPUT, @CATEGORY NVARCHAR(50) OUTPUT , @CAPTION NVARCHAR(50) OUTPUT AS SELECT @ALBUMID = A.AlbumID,@CATEGORY=A.Category,@CAPTION=TMP.Caption FROM Albums A CROSS APPLY ( SELECT top 1 * FROM Photos WHERE AlbumID=A.AlbumID )TMP order by A.AlbumID DECLARE @x INT,@y NVARCHAR(50),@z NVARCHAR(50) EXEC USP_GETFirstPhoto @x output,@y output,@z output select @x,@y,@z
but when i exec this proc i have a recorde not a result set
with this query i have resultset
SELECT * FROM Photos CROSS APPLY ( SELECT TOP 1 AlbumID FROM Photos GROUP BY AlbumID)TMP
I have a procedure that im going to be calling on my page load, i will pass an id to it and it will return up to 6 records. I need to set a session for each record returned.
Can i do that within my page_load event to pass the value, and set the sessions?
If no results are returned, then that session will be 0. So in other words, regardless there will always be 6 sessions that need to be set, either with the results returned or with 0.
I have the following query, the relationship is mutiple pictures per dog and multiple dogs per registered User. the query below will return dogs that belong to users that have not expired. the problem is that some users have many dogs and other users only have one dog listed, the query below will return a record for every dog. What I would like to do is return a random dog per user and only one dog per user each time the query executes. therefore if I have 10 users and 50 dogs I would like my quesry to only return 10 dogs one beloinging to each user, and the next time the quesry executes it would be nice if it once again return 10 dogs but a different 10 dogs 1/per user where it was able..
I have the default membership table that was added automatically, then just used server explorer to add more columns, like FirstName, LastName, etc. In my code I can access all the default columns, but not the ones I created. Any thing special I need to do?
Here is how I access the table. using user. gives me all columns, but the one I created.
string userName = User.Identity.Name; MembershipUser user = (MembershipUser)System.Web.Security.Membership.GetUser(userName).ProviderUserKey;
I have a Access DB. I have relations with two tables. For example In my table1 I have three columns as T1ID, Name, Description and Tbale2 I have three column as T2ID, T1ID which is a foreignkey from Table1 and desc.
What I want is that : for example, I wanna copy the columns from table2 which has the value of 2 under the foreignkey field and I wanna insert them into table2 again with the value of 3 under the foreignkey field !
