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Views: 1812 | Replies: 3
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Working With Dataset 
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Join Date: Nov 2006
Posts: 692
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Practically a Master Poster
Hi,
Refine ur Query, which u use to fill the Dataset:
check this:
Regards
Veena
Refine ur Query, which u use to fill the Dataset:
check this:
MyStr = "Select Distinct FldName From MyTable" OCmd = New OleDbCommand(MyStr, oConn) da.SelectCommand = OCmd da.Fill(oDS, "t1")
Regards
Veena
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Join Date: Jul 2007
Posts: 9
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Newbie Poster
Re: Working With Dataset hi veena
im fetching records from excel file
"distinct" keyword is not support by that
and i have to handle more than 30000 records
i have to use "select query" inside that dataset help me out in thiz way
a column i have to filter has repeated records so i have to use "select distinct " inside that dataset i dont know how to do it
im fetching records from excel file
"distinct" keyword is not support by that
and i have to handle more than 30000 records
i have to use "select query" inside that dataset help me out in thiz way
a column i have to filter has repeated records so i have to use "select distinct " inside that dataset i dont know how to do it
Regards
Baskar
Baskar
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Join Date: Jan 2007
Posts: 4
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Newbie Poster
The only way is to handle selection with a function:
Public Shared Function SelectDistinct(ByVal SourceTable As DataTable, ByVal ParamArray FieldNames() As String) As DataTable
Dim lastValues() As Object
Dim newTable As DataTable
If FieldNames Is Nothing OrElse FieldNames.Length = 0 Then
Throw New ArgumentNullException("FieldNames")
End If
lastValues = New Object(FieldNames.Length - 1) {}
newTable = New DataTable
For Each field As String In FieldNames
newTable.Columns.Add(field, SourceTable.Columns(field).DataType)
Next
For Each Row As DataRow In SourceTable.Select("", String.Join(", ", FieldNames))
If Not fieldValuesAreEqual(lastValues, Row, FieldNames) Then
newTable.Rows.Add(createRowClone(Row, newTable.NewRow(), FieldNames))
setLastValues(lastValues, Row, FieldNames)
End If
Next
Return newTable
End Function
Private Shared Function fieldValuesAreEqual(ByVal lastValues() As Object, ByVal currentRow As DataRow, ByVal fieldNames() As String) As Boolean
Dim areEqual As Boolean = True
For i As Integer = 0 To fieldNames.Length - 1
If lastValues(i) Is Nothing OrElse Not lastValues(i).Equals(currentRow(fieldNames(i))) Then
areEqual = False
Exit For
End If
Next
Return areEqual
End Function
Private Shared Function createRowClone(ByVal sourceRow As DataRow, ByVal newRow As DataRow, ByVal fieldNames() As String) As DataRow
For Each field As String In fieldNames
newRow(field) = sourceRow(field)
Next
Return newRow
End Function
Private Shared Sub setLastValues(ByVal lastValues() As Object, ByVal sourceRow As DataRow, ByVal fieldNames() As String)
For i As Integer = 0 To fieldNames.Length - 1
lastValues(i) = sourceRow(fieldNames(i))
Next
End Sub
Public Shared Function SelectDistinct(ByVal SourceTable As DataTable, ByVal ParamArray FieldNames() As String) As DataTable
Dim lastValues() As Object
Dim newTable As DataTable
If FieldNames Is Nothing OrElse FieldNames.Length = 0 Then
Throw New ArgumentNullException("FieldNames")
End If
lastValues = New Object(FieldNames.Length - 1) {}
newTable = New DataTable
For Each field As String In FieldNames
newTable.Columns.Add(field, SourceTable.Columns(field).DataType)
Next
For Each Row As DataRow In SourceTable.Select("", String.Join(", ", FieldNames))
If Not fieldValuesAreEqual(lastValues, Row, FieldNames) Then
newTable.Rows.Add(createRowClone(Row, newTable.NewRow(), FieldNames))
setLastValues(lastValues, Row, FieldNames)
End If
Next
Return newTable
End Function
Private Shared Function fieldValuesAreEqual(ByVal lastValues() As Object, ByVal currentRow As DataRow, ByVal fieldNames() As String) As Boolean
Dim areEqual As Boolean = True
For i As Integer = 0 To fieldNames.Length - 1
If lastValues(i) Is Nothing OrElse Not lastValues(i).Equals(currentRow(fieldNames(i))) Then
areEqual = False
Exit For
End If
Next
Return areEqual
End Function
Private Shared Function createRowClone(ByVal sourceRow As DataRow, ByVal newRow As DataRow, ByVal fieldNames() As String) As DataRow
For Each field As String In fieldNames
newRow(field) = sourceRow(field)
Next
Return newRow
End Function
Private Shared Sub setLastValues(ByVal lastValues() As Object, ByVal sourceRow As DataRow, ByVal fieldNames() As String)
For i As Integer = 0 To fieldNames.Length - 1
lastValues(i) = sourceRow(fieldNames(i))
Next
End Sub
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