Sub Page_Load(sender As Object, e As EventArgs)
Dim Conn As OleDbConnection
Dim Provider = "Provider=Microsoft.Jet.OLEDB.4.0"
Dim Database = "Data Source=" & Server.MapPath( "admin/shop.mdb" )
Conn = New OleDbConnection( Provider & ";" & DataBase )
dim strSql1 = "select * from aclass "
Dim mycommand1 As oledbCommand = New oledbCommand(strSql1, conn)
Conn.Open()
Dim myReader1 As oledbDataReader = mycommand1.ExecuteReader(CommandBehavior.CloseConnection)
While myReader1.Read()
dim contact=contact & "<table><tr><td>" & myReader1.GetValue(1).ToString & "</td>"
dim strSql = "select bclassname from bclass where a1='" & myReader1.GetValue(1).ToString &"'"
Dim mycommand As oledbCommand = New oledbCommand(strSql, conn)
conn.Open()
Dim myReader As oledbDataReader = mycommand.ExecuteReader(CommandBehavior.CloseConnection)
While myReader.Read()
contact=contact & "<td>" & myReader.GetValue(1).ToString & "</td>"
End While
conn.Close()
contact=contact & "</tr></table>"
End While
conn.Close()System.InvalidOperationException: 连接已经打开(state=Open, Fetching)。
Dim Conn As OleDbConnection
Dim Provider = "Provider=Microsoft.Jet.OLEDB.4.0"
Dim Database = "Data Source=" & Server.MapPath( "admin/shop.mdb" )
Conn = New OleDbConnection( Provider & ";" & DataBase )
dim strSql1 = "select * from aclass "
Dim mycommand1 As oledbCommand = New oledbCommand(strSql1, conn)
Conn.Open()
Dim myReader1 As oledbDataReader = mycommand1.ExecuteReader(CommandBehavior.CloseConnection)
While myReader1.Read()
dim contact=contact & "<table><tr><td>" & myReader1.GetValue(1).ToString & "</td>"
dim strSql = "select bclassname from bclass where a1='" & myReader1.GetValue(1).ToString &"'"
Dim mycommand As oledbCommand = New oledbCommand(strSql, conn)
conn.Open()
Dim myReader As oledbDataReader = mycommand.ExecuteReader(CommandBehavior.CloseConnection)
While myReader.Read()
contact=contact & "<td>" & myReader.GetValue(1).ToString & "</td>"
End While
conn.Close()
contact=contact & "</tr></table>"
End While
conn.Close()System.InvalidOperationException: 连接已经打开(state=Open, Fetching)。
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后面加个;号看看
Dim Provider = "Provider=Microsoft.Jet.OLEDB.4.0;"
因为你开始已经打开数据库连接,切没有关闭,所以会触发异常要么你就在conn.open 的上面加上conn.close;conn.dispose
总之不要保持长连接就是了
conn.Open()连接在上面已经打开过了。
没关闭前就无须再次打开。
但是第二次打开前你没有关闭。所以会出现这个错误。
如果你关闭了你的代码功能不能实现。
就是只能一个reader和一个大开的connection关联。在asp.net2.0里可以实现两个reader用一个连接,但是必须书序执行,不能并发,而且需要用sqlserver2005.
而且这个方法好像有争议。