HOW TO:给DataTable添加一自增列至首列
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Author:水如烟
示例
Dim db As New LzmTW.Data.AccessOleDbDatabase("G:/OfficeNorthwind.mdb")
Dim cm As DbCommand = db.CreateCommand("Employees")
cm.Connection.Open()
Dim table As DataTable = cm.ExecuteReader.GetSchemaTable
cm.Connection.Dispose()
cm.Dispose()
Dim nowTable As DataTable = TableHelper.AddAutoIncreaseColumn(table, "NO", 1)
Dim cm As DbCommand = db.CreateCommand("Employees")
cm.Connection.Open()
Dim table As DataTable = cm.ExecuteReader.GetSchemaTable
cm.Connection.Dispose()
cm.Dispose()
Dim nowTable As DataTable = TableHelper.AddAutoIncreaseColumn(table, "NO", 1)
代码:
Public Class TableHelper
Sub New()
End Sub
Public Shared Function AddAutoIncreaseColumn(ByVal table As DataTable, ByVal columnName As String, Optional ByVal seed As Integer = 0, Optional ByVal [step] As Integer = 1) As DataTable
Dim autoIncreaseColumn As New DataColumn(columnName, GetType(Integer))
With autoIncreaseColumn
.AutoIncrement = True
.AutoIncrementSeed = seed
.AutoIncrementStep = [step]
.ReadOnly = True
End With
Dim tmpTable As DataTable = table.Clone
Sub New()
End Sub
Public Shared Function AddAutoIncreaseColumn(ByVal table As DataTable, ByVal columnName As String, Optional ByVal seed As Integer = 0, Optional ByVal [step] As Integer = 1) As DataTable
Dim autoIncreaseColumn As New DataColumn(columnName, GetType(Integer))
With autoIncreaseColumn
.AutoIncrement = True
.AutoIncrementSeed = seed
.AutoIncrementStep = [step]
.ReadOnly = True
End With
Dim tmpTable As DataTable = table.Clone
tmpTable.PrimaryKey = Nothing
Dim result As New DataTable(table.TableName)
result.Columns.Add(autoIncreaseColumn)
Dim tmpCol As DataColumn
For Each col As DataColumn In table.Columns
tmpCol = tmpTable.Columns(col.ColumnName)
tmpTable.Columns.Remove(tmpCol)
result.Columns.Add(tmpCol)
Next
result.Merge(table)
Return result
End Function
End Class
Dim result As New DataTable(table.TableName)
result.Columns.Add(autoIncreaseColumn)
Dim tmpCol As DataColumn
For Each col As DataColumn In table.Columns
tmpCol = tmpTable.Columns(col.ColumnName)
tmpTable.Columns.Remove(tmpCol)
result.Columns.Add(tmpCol)
Next
result.Merge(table)
Return result
End Function
End Class
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