I have a datatable and i need to put CONTAINS condition in it.Now am retrieving datatable rows using below query
DataRow[] resultss = dtDocument.Select("DocumentElementText='" + columnValue + "'");
but i need to put condition like contains in this query for retrieving values from datatable.
above is my datatable. this query dtDocument.Select("DocumentElementText='New Package'"); will return me the first row from the datatable.What i need is , i need to retrieve the row which contains <td>NAME</td> from this datatable. How to retrieve the row ..??
Regards
Arshad
try this
DataRow[] resultss = dt.AsEnumerable().Where(row => row.Field<string>("DocumentElementText").Contains("Enter Your String Here")).Select(row => row).ToArray<DataRow>();
This is my code:
SqlCommand vmpCmd = new SqlCommand("sp", connectionstring);
SqlDataAdapter DAvmp = new SqlDataAdapter(vmpCmd);
DataSet DSvmp = new DataSet();
DSvmp.Clear();
DAvmp.Fill(DSvmp);
DataTable table;
table = DSvmp.Tables[0];
from that table I need to take all the rows that its Campaign column exists in this list List<string> compaines = new List<string>();
What have I tried
I tried this:
table = (from row in table.AsEnumerable()
where compaines.Contains(row.Field<string>("Campaign"))
select row);
but I got this exception on the select:
Cannot implicitly convert type 'System.Data.EnumerableRowCollection<System.Data.DataRow>' to 'System.Data.DataTable'
If you want to convert an IEnumerable<DataRow> to a DataTable you can use CopyToDataTable:
var filteredRows = table.AsEnumerable()
.Where(row => compaines.Contains(row.Field<string>("Campaign")));
table = filteredRows.CopyToDataTable();
But instead of filtering when you've already retrieved all records i would do that in the database. Here's a nice trick to build parameters from a List<string>.
Use CopyToDataTable extension method to convert IEnumerable<DataRow> to DataTable
table = (from row in table.AsEnumerable()
where compaines.Contains(row.Field<string>("Campaign"))
select row).CopyToDataTable();
Get the values in var data type like this as LINQ returns System.Data.EnumerableRowCollection<System.Data.DataRow which cannot be implicity converted to Datatable type
var filteredTable = (from row in table.AsEnumerable()
where compaines.Contains(row.Field<string>("Campaign"))
select row);
If you want the retrieved records for other operations then its fine otherwise it's better to use filter in your query and for that there are below methods:
You can use parameterized query
You can build your query string using String.Join() from your List
I have a dataset that gets populated from a stored proc in sql server. I have a column that has lets say has a set of values. I do not know what those values are. All I know is that they of the type "string". I want to extract all the distinct values from that column.
You can use a DataView and set its RowFilter to the desired condition:
var view = new DataView(dataset.Tables["Table"]);
view.RowFilter = "Column = 42";
UPDATE: based on your updated question, you can use LINQ:
var table = dataset.Tables["Table"].AsEnumerable();
var distinctValuesForColumn =
table.Select(row => (string)row["Column"]).Distinct();
You can simply use Select method of the DataTable :
DataRow[] extractedRows =
yourDataSet.Tables["YourTableName"].Select("YourColumnName = 123");
You can also use Linq to query your datatables. Here is a link to some examples on the MS site - http://msdn.microsoft.com/en-us/vbasic/bb688086.aspx
I hope below statement will serve your purpose
ds.Tables["TableName"].DefaultView.ToTable( true, "columnName"); //For Dataset (true means distinct)
OR
`ds.Tables[0].DefaultView.ToTable( true, "columnName");
//For Dataset where tableindex is 0
OR
dt.DefaultView.ToTable( true, "columnName"); //For Datatable
//Syntax is like Datatable.DefaultView.ToTable( Distinct true/false, “ColumnName”);
MSDN : http://msdn.microsoft.com/en-us/library/wec2b2e6.aspx
I'm trying to narrow down the rows that are in my DataView based on a relation with another table, and the RowFilter I'm using is as follows;
dv = new DataView(myDS.myTable,
"id IN (SELECT DISTINCT parentID FROM myOtherTable)",
"name asc",
DataViewRowState.CurrentRows);
"myTable" and "myOther" table are related via myTable.ID and myOtherTable.parentID, and so the idea is that the DataView should only contain rows from "myTable" which have corresponding child rows in "myOtherTable".
Unfortunately, I'm getting this error;
Syntax error: Missing operand after
'DISTINCT' operator.
The SQL is fine as far as I am aware, so I'm wondering is there some limitation on using the DISTINCT keyword as part of RowFilter's SQL? Anyone have any idea?
Unfortunately, I don't think you can perform a subquery in a DataView's filter expression. You're only allowed to use a subset of SQL in some expressions (documented here).
You'll probably need to perform your subquery (SELECT DISTINCT parentID FROM myOtherTable) separately.
This article describes the problem and a possible solution.
Unfortunately you can't do it that way, as the RowFilter property does not support the distinct keyword. Here is the list of expressions you can perform in a RowFilter (which is just a DataColumn Expression): http://msdn.microsoft.com/en-us/library/system.data.datacolumn.expression.aspx
DataViews have a ToTable method, and several overloads take a boolean to specify whether to return only the distinct rows.
Here is one method: http://msdn.microsoft.com/en-us/library/wec2b2e6.aspx
Here is how you would use it:
DataTable newDataTable = myDataView.ToTable( true, [array of column names as strings] );
DataView dvBindAssignedByDropDown = new DataView();
DataTable dtBindAssignedByDropDown = new DataTable();
dvBindAssignedByDropDown = ds.Tables[0].DefaultView;
string[] strColnames=new string[2];
strColnames[0] = "RedNames";
strColnames[1] = "RedValues";
dtBindAssignedByDropDown = dvBindAssignedByDropDown.ToTable(true, strColnames);
ddlAssignedby.DataTextField = "RedNamesNames";
ddlAssignedby.DataValueField = "RedNames";
ddlAssignedby.DataSource = dtBindAssignedByDropDown;
ddlAssignedby.DataBind();
ddlAssignedby.Items.Insert(0, "Assigned By");
ddlAssignedby.Items[0].Value = "0";
the following code is extracting distinct values/records from a table/dataview, namely(PROD_DESP_TRN) having field(CONTAINER_NO)
Finally, this code is filling a combobox(cmbContainerNo) with unique values/records
Form Level Declaration:
Dim dsLocal As DataSet
Dim dvm As DataViewManager
Private Sub FillcomboContainer()
Try
Dim dv As DataView = New DataView
cmbContainerNo.DataSource = Nothing
dv = dvm.CreateDataView(dsLocal.Tables("PROD_DESP_TRN"))
dv.Sort = "CONTAINER_NO"
cmbContainerNo.DataSource = dv.ToTable(True, "CONTAINER_NO")
cmbContainerNo.DisplayMember = "CONTAINER_NO"
Catch ex As Exception
MsgBox(ex.Message)
Finally
End Try
End Sub
Try just leaving out the "DISTINCT". In this case, the results should be the same with or without. Troubleshoot from there.
I'm trying to perform a LINQ query on a DataTable object and bizarrely I am finding that performing such queries on DataTables is not straightforward. For example:
var results = from myRow in myDataTable
where results.Field("RowNo") == 1
select results;
This is not allowed. How do I get something like this working?
I'm amazed that LINQ queries are not allowed on DataTables!
You can't query against the DataTable's Rows collection, since DataRowCollection doesn't implement IEnumerable<T>. You need to use the AsEnumerable() extension for DataTable. Like so:
var results = from myRow in myDataTable.AsEnumerable()
where myRow.Field<int>("RowNo") == 1
select myRow;
And as #Keith says, you'll need to add a reference to System.Data.DataSetExtensions
AsEnumerable() returns IEnumerable<DataRow>. If you need to convert IEnumerable<DataRow> to a DataTable, use the CopyToDataTable() extension.
Below is query with Lambda Expression,
var result = myDataTable
.AsEnumerable()
.Where(myRow => myRow.Field<int>("RowNo") == 1);
var results = from DataRow myRow in myDataTable.Rows
where (int)myRow["RowNo"] == 1
select myRow
It's not that they were deliberately not allowed on DataTables, it's just that DataTables pre-date the IQueryable and generic IEnumerable constructs on which Linq queries can be performed.
Both interfaces require some sort type-safety validation. DataTables are not strongly typed. This is the same reason why people can't query against an ArrayList, for example.
For Linq to work you need to map your results against type-safe objects and query against that instead.
As #ch00k said:
using System.Data; //needed for the extension methods to work
...
var results =
from myRow in myDataTable.Rows
where myRow.Field<int>("RowNo") == 1
select myRow; //select the thing you want, not the collection
You also need to add a project reference to System.Data.DataSetExtensions
I realize this has been answered a few times over, but just to offer another approach:
I like to use the .Cast<T>() method, it helps me maintain sanity in seeing the explicit type defined and deep down I think .AsEnumerable() calls it anyways:
var results = from myRow in myDataTable.Rows.Cast<DataRow>()
where myRow.Field<int>("RowNo") == 1 select myRow;
or
var results = myDataTable.Rows.Cast<DataRow>()
.FirstOrDefault(x => x.Field<int>("RowNo") == 1);
As noted in comments, does not require System.Data.DataSetExtensions or any other assemblies (Reference)
var query = from p in dt.AsEnumerable()
where p.Field<string>("code") == this.txtCat.Text
select new
{
name = p.Field<string>("name"),
age= p.Field<int>("age")
};
the name and age fields are now part of the query object and can be accessed like so: Console.WriteLine(query.name);
Using LINQ to manipulate data in DataSet/DataTable
var results = from myRow in tblCurrentStock.AsEnumerable()
where myRow.Field<string>("item_name").ToUpper().StartsWith(tbSearchItem.Text.ToUpper())
select myRow;
DataView view = results.AsDataView();
//Create DataTable
DataTable dt= new DataTable();
dt.Columns.AddRange(new DataColumn[]
{
new DataColumn("ID",typeof(System.Int32)),
new DataColumn("Name",typeof(System.String))
});
//Fill with data
dt.Rows.Add(new Object[]{1,"Test1"});
dt.Rows.Add(new Object[]{2,"Test2"});
//Now Query DataTable with linq
//To work with linq it should required our source implement IEnumerable interface.
//But DataTable not Implement IEnumerable interface
//So we call DataTable Extension method i.e AsEnumerable() this will return EnumerableRowCollection<DataRow>
// Now Query DataTable to find Row whoes ID=1
DataRow drow = dt.AsEnumerable().Where(p=>p.Field<Int32>(0)==1).FirstOrDefault();
//
Try this simple line of query:
var result=myDataTable.AsEnumerable().Where(myRow => myRow.Field<int>("RowNo") == 1);
You can use LINQ to objects on the Rows collection, like so:
var results = from myRow in myDataTable.Rows where myRow.Field("RowNo") == 1 select myRow;
This is a simple way that works for me and uses lambda expressions:
var results = myDataTable.Select("").FirstOrDefault(x => (int)x["RowNo"] == 1)
Then if you want a particular value:
if(results != null)
var foo = results["ColName"].ToString()
Try this
var row = (from result in dt.AsEnumerable().OrderBy( result => Guid.NewGuid()) select result).Take(3) ;
Most likely, the classes for the DataSet, DataTable and DataRow are already defined in the solution. If that's the case you won't need the DataSetExtensions reference.
Ex. DataSet class name-> CustomSet, DataRow class name-> CustomTableRow (with defined columns: RowNo, ...)
var result = from myRow in myDataTable.Rows.OfType<CustomSet.CustomTableRow>()
where myRow.RowNo == 1
select myRow;
Or (as I prefer)
var result = myDataTable.Rows.OfType<CustomSet.CustomTableRow>().Where(myRow => myRow.RowNo);
var results = from myRow in myDataTable
where results.Field<Int32>("RowNo") == 1
select results;
In my application I found that using LINQ to Datasets with the AsEnumerable() extension for DataTable as suggested in the answer was extremely slow. If you're interested in optimizing for speed, use James Newtonking's Json.Net library (http://james.newtonking.com/json/help/index.html)
// Serialize the DataTable to a json string
string serializedTable = JsonConvert.SerializeObject(myDataTable);
Jarray dataRows = Jarray.Parse(serializedTable);
// Run the LINQ query
List<JToken> results = (from row in dataRows
where (int) row["ans_key"] == 42
select row).ToList();
// If you need the results to be in a DataTable
string jsonResults = JsonConvert.SerializeObject(results);
DataTable resultsTable = JsonConvert.DeserializeObject<DataTable>(jsonResults);
Example on how to achieve this provided below:
DataSet dataSet = new DataSet(); //Create a dataset
dataSet = _DataEntryDataLayer.ReadResults(); //Call to the dataLayer to return the data
//LINQ query on a DataTable
var dataList = dataSet.Tables["DataTable"]
.AsEnumerable()
.Select(i => new
{
ID = i["ID"],
Name = i["Name"]
}).ToList();
For VB.NET The code will look like this:
Dim results = From myRow In myDataTable
Where myRow.Field(Of Int32)("RowNo") = 1 Select myRow
IEnumerable<string> result = from myRow in dataTableResult.AsEnumerable()
select myRow["server"].ToString() ;
Try this...
SqlCommand cmd = new SqlCommand( "Select * from Employee",con);
SqlDataReader dr = cmd.ExecuteReader( );
DataTable dt = new DataTable( "Employee" );
dt.Load( dr );
var Data = dt.AsEnumerable( );
var names = from emp in Data select emp.Field<String>( dt.Columns[1] );
foreach( var name in names )
{
Console.WriteLine( name );
}
You can get it work elegant via linq like this:
from prod in TenMostExpensiveProducts().Tables[0].AsEnumerable()
where prod.Field<decimal>("UnitPrice") > 62.500M
select prod
Or like dynamic linq this (AsDynamic is called directly on DataSet):
TenMostExpensiveProducts().AsDynamic().Where (x => x.UnitPrice > 62.500M)
I prefer the last approach while is is the most flexible.
P.S.: Don't forget to connect System.Data.DataSetExtensions.dll reference
you can try this, but you must be sure the type of values for each Column
List<MyClass> result = myDataTable.AsEnumerable().Select(x=> new MyClass(){
Property1 = (string)x.Field<string>("ColumnName1"),
Property2 = (int)x.Field<int>("ColumnName2"),
Property3 = (bool)x.Field<bool>("ColumnName3"),
});
I propose following solution:
DataView view = new DataView(myDataTable);
view.RowFilter = "RowNo = 1";
DataTable results = view.ToTable(true);
Looking at the DataView Documentation, the first thing we can see is this:
Represents a databindable, customized view of a DataTable for sorting, filtering, searching, editing, and navigation.
What I am getting from this is that DataTable is meant to only store data and DataView is there enable us to "query" against the DataTable.
Here is how this works in this particular case:
You try to implement the SQL Statement
SELECT *
FROM myDataTable
WHERE RowNo = 1
in "DataTable language". In C# we would read it like this:
FROM myDataTable
WHERE RowNo = 1
SELECT *
which looks in C# like this:
DataView view = new DataView(myDataTable); //FROM myDataTable
view.RowFilter = "RowNo = 1"; //WHERE RowNo = 1
DataTable results = view.ToTable(true); //SELECT *