Question

VB.NET上面的问题（在调用“Fill”前，SelectCommand 属性尚未初始化）

Dim OleDbCommand1 As System.Data.OleDb.OleDbCommand
Dim oledbdataadapter As System.Data.OleDb.OleDbDataAdapter
Dim dataadapter As System.Data.OleDb.OleDbDataAdapter

OleDbConnection1.ConnectionString = "Provider = Microsoft.Jet.OLEDB.4.0;Data Source=d:\My Documents\Visual Studio 2005\Projects\WindowsApplication4\WindowsApplication4\db.mdb" 'ACCESS链接字符串

OleDbCommand1 = New System.Data.OleDb.OleDbCommand

OleDbConnection1.Open() '打开数据库

OleDbCommand1.CommandText = "Select * from 联系人" '要执行的SQL语句

oledbdataadapter = New OleDb.OleDbDataAdapter(OleDbConnection1.ConnectionString, OleDbConnection1) '创建DataAdapter数据适配器实例

Dim customerOrders As DataSet = New DataSet("CustomerOrders") '创建DataSet实例()

dataadapter = New System.Data.OleDb.OleDbDataAdapter

dataadapter.Fill(New DataSet, "联系人") '使用DataAdapter的Fill方法(填充)，调用SELECT命令

OleDbConnection1.Close() '关闭数据库

为什么我在运行的时候出现 在调用“Fill”前，SelectCommand 属性尚未初始化？怎么修改？

Answer 1

Dim OleDbCommand1 As System.Data.OleDb.OleDbCommand
Dim oledbdataadapter As System.Data.OleDb.OleDbDataAdapter
Dim dataadapter As System.Data.OleDb.OleDbDataAdapter

OleDbConnection1.ConnectionString = "Provider = Microsoft.Jet.OLEDB.4.0;Data Source=d:\My Documents\Visual Studio 2005\Projects\WindowsApplication4\WindowsApplication4\db.mdb"

OleDbCommand1 = New System.Data.OleDb.OleDbCommand

OleDbCommand1.CommandText = "Select * from 联系人"

OleDbCommand1.Connection=OleDbConnection1

OleDbConnection1.Open()

dataadapter = New System.Data.OleDb.OleDbDataAdapter

dataadapter.SelectCommand = OleDbCommand1

Dim customerOrders As DataSet = New DataSet("CustomerOrders")

dataadapter.Fill(customerOrders , "联系人")

OleDbConnection1.Close()

Answer 2

OleDbCommand1.connection=OleDbConnection1