Asp.net - How To Correctly Filter A Datatable (datatable.select)
Jun 17, 2010
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.
have created a data table as global data table for the session. So when the user selects the drop down Address Type Main , Street, Emergency - I want the Address text fields to display based on user selects. So, for my dropdown i have datavaluefield column as addressid. And the datasource for this is datatable. I was having problems converting from datatable to dataview. Does anyone know how to do this? I was geting errors cant convert from datatable to dataview. I was choosing dataview because you have the filter option. But then I saw you could also select in data table. So I am trying to select a row in datatable with select with expression like this:
Dim dtAddress As New DataTable dtAddress = GlobalVariables.AddressTable
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";
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:
public static DataTable GetDataTable(SqlCommand sqlCmd) { DataTable tblMyTable = new DataTable(); DataSet myDataSet = new DataSet(); try { //1. Create connection mSqlConnection = new SqlConnection(mStrConnection); //2. Open connection mSqlConnection.Open(); mSqlCommand = new SqlCommand(); mSqlCommand = sqlCmd; //3. Assign Connection mSqlCommand.Connection = mSqlConnection; //4. Create/Set DataAdapter mSqlDataAdapter = new SqlDataAdapter(); mSqlDataAdapter.SelectCommand = mSqlCommand; //5. Populate DataSet mSqlDataAdapter.Fill(myDataSet, "DataSet"); tblMyTable = myDataSet.Tables[0]; } catch (Exception ex) { } finally { //6. Clear objects if ((mSqlDataAdapter != null)) { mSqlDataAdapter.Dispose(); } if ((mSqlCommand != null)) { mSqlCommand.Dispose(); } if ((mSqlConnection != null)) { mSqlConnection.Close(); mSqlConnection.Dispose(); } } //7. Return DataSet return tblMyTable; }
I use the above code to return records from database. The above snippet would run in web application which expected to have around 5000 visitors daily. The records returned reach 20,000 or over. The returned records are viewed (read-only) in paged GridView.
Would it be better to use DataReader instead of DataTable?
NOTE: two columns in the GridView are hyperlinked.
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 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 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 have the dataset with one table.Table contains three column like 'Name','Location','Pin'.I would like to move the data from another table based on schema.
If I am passed a datatable and I cant change the column structure..is there anyway to set an existing column to a Primary key so I can easily Find() the row I am looking for?
im trying to copying specific record from one datatable to another datatable i used below code
public System.Data.DataTable selectspecificdatarow(System.Data.DataTable dtg, int count, int startindex) { System.Data.DataTable dtn = dtg.Clone(); for (int i =startindex; i < count; i++)
[Code]....
its taking too long time in cloneing is there any better way to do this task which is Time effecent
how to join two datatable datas into one datatable to show in one gridview
i.e in 1 datatable i have username and pwd and in another datatable i have that user details. how to show all these in one datatable to get those values display in gridview(asp.net)
I have records in the datatable which I have retreived from xml file.
Dim docDataSet As New DataSet Dim docReader As New XmlDocument Dim xnl As XmlNodeList docReader.Load("UserProfile.xml") xnl = docReader.SelectNodes("/Users/user") For Each xn As XmlNode In xnl Dim xr As New XmlNodeReader(xn) docDataSet.ReadXml(xr) Next xn Dim Dm_table As DataTable = ds.tables(0)
Now what I want to do is execute a select query like below:
Select * from user where userid in (select ID from Dm_table)
Retreive the records from the User table based on the ID's in the datatable.
I have a dataset generated from xml from a web service.Data needs to be sorted by date order descending, I cannot get the web service changed so thought I'd try:
Code: repeater1.DataSource = dsCombinedBlock.Tables(2).Select("Status < 3 and status <> 99", "DateReceived desc") However the dates are treated as a string so the results look like
I have a DataTable of available time slots. I have another DataTable of reserved time slots. I need to remove from the list of available slots the ones that have been reserved. The blocks are in 15 minute increments, but one of my problems is that the reservation can be longer than 15 minutes. I've had some luck removing one or two, but not all of the required columns.
