Create Auto-Increment field using a language extension

[kevininstructor]

There are times when you may need to create a DataTable to fill on the fly which requires a auto incrementing primary key. To make life simple I created several language extensions.

The first creates one with the field name of Identifier

AddPrimaryKey(ByVal sender As DataColumnCollection)

Next, provides a parameter to supply the column name

AddPrimaryKey(ByVal sender As DataColumnCollection, ByVal ColumnName As String)

Supply column name and seed

Public Sub AddPrimaryKey(ByVal sender As DataColumnCollection, _
                            ByVal ColumnName As String, ByVal Seed As Integer)

Lastly supply column name, seed and step

Public Sub AddPrimaryKey(ByVal sender As DataColumnCollection, _
                         ByVal ColumnName As String, ByVal Seed As Integer, _
                         ByVal StepAmount As Integer)

Example usage

   Sub Main()

      Dim Table1 As New DataTable
      Table1.Columns.AddPrimaryKey("ID", 10, 20)
      Table1.Columns.Add(New DataColumn("LastName", _
                                        GetType(System.String)))

      Table1.Rows.Add(New Object() {Nothing, "Gallagher"})
      Table1.Rows.Add(New Object() {Nothing, "Smith"})
      Table1.Rows.Add(New Object() {Nothing, "Jones"})

      Console.WriteLine("Example 1: AddPrimaryKey(""ID"", 10, 20)")
      For Each Row As DataRow In Table1.Rows
         Console.WriteLine("ID={0} Last Name {1}", _
                           Row("ID"), _
                           Row("LastName"))
      Next

      Console.WriteLine()
      Console.WriteLine("Example 2: AddPrimaryKey()")
      Dim Table2 As New DataTable
      Table2.Columns.AddPrimaryKey()
      Table2.Columns.Add(New DataColumn("LastName", _
                                        GetType(System.String)))


      Table2.Rows.Add(New Object() {Nothing, "Smith"})
      Table2.Rows.Add(New Object() {Nothing, "Gallagher"})
      Table2.Rows.Add(New Object() {Nothing, "Jones"})
      For Each Row As DataRow In Table2.Rows
         Console.WriteLine("ID={0} Last Name {1}", _
                           Row("Identifier"), _
                           Row("LastName"))
      Next

      Console.WriteLine()
      Console.ReadLine()

   End Sub