关于Try。。End Try

[pwalai]

Try
mycon.Open()
myreader = mycmd.ExecuteReader
Return myreader
Catch e As Data.OleDb.OleDbException
Throw New Exception(e.Message)
Finally
mycmd.Dispose()

End Try
mycon.Close()


和

Try
mycon.Open()
myreader = mycmd.ExecuteReader
Return myreader
Catch e As Data.OleDb.OleDbException
Throw New Exception(e.Message)
Finally
mycmd.Dispose()
mycon.Close()
End Try

有什么区别，为什么在使用时前面的对

[evonne0102]

try //运行程序代码
end try //结束
finally// 关闭任何已经打开的链接。

[pwalai]

如果采用第二种，那么Return myreader 接受他的reader就是会说连接关闭。为什么会这样

[i三千]

差别只是mycon.Close()是否在finally块中。

finally是表示，不管try执行时是否发生错误，都要执行的程序块。

按你的程序来看，应该是一样的。

[i三千]

你应该给个完整点的代码。这点还是看不出来。

[pwalai]

Public Shared Function TheReader(ByVal mysql As String) As Data.OleDb.OleDbDataReader
Dim connstr As String = System.Configuration.ConfigurationManager.AppSettings("ConnString")
Dim mycon As Data.OleDb.OleDbConnection = New Data.OleDb.OleDbConnection(connstr)
Dim mycmd As Data.OleDb.OleDbCommand = New Data.OleDb.OleDbCommand(mysql, mycon)
Dim myreader As Data.OleDb.OleDbDataReader


Try
mycon.Open()
myreader = mycmd.ExecuteReader
Return myreader
Catch e As Data.OleDb.OleDbException
Throw New Exception(e.Message)
Finally
mycmd.Dispose()

End Try
mycon.Close()
正确

Public Shared Function TheReader(ByVal mysql As String) As Data.OleDb.OleDbDataReader
Dim connstr As String = System.Configuration.ConfigurationManager.AppSettings("ConnString")
Dim mycon As Data.OleDb.OleDbConnection = New Data.OleDb.OleDbConnection(connstr)
Dim mycmd As Data.OleDb.OleDbCommand = New Data.OleDb.OleDbCommand(mysql, mycon)
Dim myreader As Data.OleDb.OleDbDataReader


Try
mycon.Open()
myreader = mycmd.ExecuteReader
Return myreader
Catch e As Data.OleDb.OleDbException
Throw New Exception(e.Message)
Finally
mycmd.Dispose()
mycon.Close()
End Try

错误
都是要调要这个函数

[pwalai]

自己顶

[pwalai]

再顶