Many times I need to manipulate with DataTable after I get data from database using adapter.Fill(table).
Usually I calculate data in DataTable by using loops. But I know that there is simpler way using LINQ. I know some basics about that just for strongly typed objects.I can't find how to do this with DataTable that is not strongly typed. How could I get all DataRow or Filtered DataTable (not just value for the field) from table for that conditions:
- where the specified field of the table contans MAX/MIN/AVG value,
- where the specified field of the table equals to some value.
I would like to implement LINQ IN ASP.NET for filter required data from datatable. I have doubt that what is right place. I have following options
At presentation layer *.aspx.cs
At our Business layer.
At our Data base layer, where query for database happen which is return as a datatable to business layer. Business layer then return the result to presentation layer.right place for LINQ because now i have to further filter data from datatable as per user selecter filters.
i could bind the data form tables to dropdownlist in asp .net using linq.
ex: var res=from n in dc. contacts where n.location==Hyd select new{n.Id,n.Name}; var res1=from n in dc. Morecontacts where n.location==Hyd select new{n.Id,n.Name}; dropdown1.Datasouce=res; dropdown1.DataTextField="Name"; dropdown1.DataValueField="Id";
Dim dt As New DataTable Dim da As New SqlDataAdapter(s, c)
c.Open() if Not IsNothing(da) Then da.Fill(dt)
[code]...
When I call da.fill I am inserting all records from my query. I was then hoping to filter them to display only those where the GroupingID is equal to 0. When I run the above code. I am presented with all the data, the filter did not work. Please can you tell me how to get this working correctly.
I create a DataTable and filter it. When I use filter1, everything works as expected. When I use filter2, everything works as expected only if the SubsectionAmount variable is less than 10. s soon as I set SubsectionAmount=10, the dr2 array returns Nothing.
Imports System.Data Partial Class FilterTest Inherits System.Web.UI.Page Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Loa [code]....
I am doing some aggregates on in memory tables using the DataTable.Compute method. It works file if there is only one filter, however when there is multiples then it does not work.
This first one works fine the second one does not.
I want to filter the DataTable. for filtering the the datatable I am passing the string parameter which contains multiple wildcards ( e.g. string strSearchValue = "test%str%g")
Prior to adding paging using PagedDataSource I had dropdownlist and search box filters for my DataList. The guts of the code in aspx page for those parameters is below:
When creating the pager using PagedDataSource I did a tutorial which did not have parameters and all the code went in the code behind page. The guts of it is below:
The pager is great but now I need to add my filters. The page wont load if I add the "SelectParameters" code (above) to my aspx page and if I simply add the "WHERE" clause to the "SELECT" clause in the code behind I get an error stating that I need to add a scalar variable.
I have found some examples through googling but nothing specific enough.
Prior to adding paging using PagedDataSource I had dropdownlist and search box filters for my DataList. The guts of the code in aspx page for those parameters is below:
HTML Code:
[code]....
The pager is great but now I need to add my filters. The page wont load if I add the "SelectParameters" code (above) to my aspx page and if I simply add the "WHERE" clause to the "SELECT" clause in the code behind I get an error stating that I need to add a scalar variable.
I've built a User Control that contains a ListView. To make it work I need to pass to it a DataTable. The columns of this DataTable need to have particular names that match up with what the ListView is expecting. I have a large DataTable that I need to massage/convert over to this different format. To do that I need to filter out columns and rename the column names. The actual data in the DataTable doesn't need to change. Is there a good way to do this without actually instantiating a new DataTable and copying the data from the large DataTable into it?
I have a ListView with Checkbox. My requirement is - When I click on any checkbox then it should return all the columns values of that row on behalf of that CheckBox. After much study I came to know that using DataTable and DataRow I can get all data of particular ID of a Row. But I am unable to work with this. My code is something like below: Â DataTable dt=new DataTable(); dt=objBAL.Get_ShoppingCartData(); ListView1.DataSource=dt.Tables[0];
I need to filter LINQ query using comboboxes and textboxes. The problem is I can't manage to get the result and I always get the empty gridview (used for showing filtered data). Can anyone help me why am I getting no results at all? I've checked the debugger and the data sent to query is valid, although, I'm not sure about "string.Empty" value.
I have a collection of objects that I want to use LINQ in order to filter out only objects that have properties that meet a certain criteria. I am not big on LINQ so I am not sure how to do this.
I create a basic LINQ statement and get the records this way
Dim lr As IEnumerable(Of LogRecord) = From rr In _logRecords where rr.username="something"
but I only want to add that where condition if someone actually filled in a textbox.
I have other conditions to do the same thing with.
I got the following query to group the table. I am wondering how to add a subtotal record with anonymous type.
string prevOriginator = string.Empty; var oOriginator = (from I in dtIssue.AsEnumerable() group I by new {RaisedBy = I.Field<string>("RaisedBy"), ItemType = I.Field<string>("ItemType")} into grp
I have a data table I need to convert to XML. I know I can use datable.WriteXML but I need to rename the elements as the column names coming from the Oracle db are ugly. I found this snippet somewhere:
[code]....
It looks like what I want but when I paste it in my code it shows an error on select Cannont convert lambda expression to type 'string' because it is not a delegate type.
I am new to linq and for that matter to C# (done a lot more vb). I am going to read the books but I need to get this done pretty quick for a project.
I wish to retrieve data from a DataTable using Linq, and I do this by first creating a DataTable with the data and then using Linq to query:
[Code]....
My problem is, that the column "enddatee" has 'holes', meaning that some rows does not have a value. This means that the convertion to DateTime will fail for some rows. How can I get around that?
I have a datatable which has been dynamically generated from FoxPro tables using a UNION Select statement. e.g.
SELECT * FROM x UNION SELECT * FROM y UNION SELECT * FROM Z ORDER By v_alue1
This produces a datatable with about 100 rows, each containing many fields, one of which is c_olor. From this datatable, I would like to select the distinct colors and then output in a dropdown.
I have a public class Color which just has one property which I can then use as the DataTextField and DataValueField for the dropdownlist
[code]...
However this never results in the distinct colors.
I have searched and searched for what I am looking for, and this seems to be one of the methods to produce a distinct set of results, but this and the others do not work.
My reasoning behind getting the colors this way, is that I need to get various other distinct values from the same UNION SELECT datasource, so would just do one DB call, cache the results, and then just used this cached datasource to retrieve all my distinct values.
