希望有人可以提供帮助。我Oracle.ManagedDataAccess.Client在我的 VB.NET 项目中使用从 Oracle 11g 数据库中提取信息。
我的项目使用硬编码的字符串，但我希望将日期时间更改为绑定变量，因为我听说服务器负载更容易。
我可以使用以下内容Using Ocommand As New OracleCommand(和硬编码的日期时间字符串，但无法Using使用直接连接和绑定变量替换以下内容：
''Build SQL Query and set variables
Dim d_start_date As DateTime = New DateTime(DateTime.Now.Year, DateTime.Now.Month, DateTime.Now.Day, DateTime.Now.Hour - 1, 0, 0)
Dim p_start_date As OracleParameter = New OracleParameter
p_start_date.OracleDbType = OracleDbType.Date
p_start_date.Value = d_start_date
p_start_date.ParameterName = "fromDateParam"
Dim d_end_date As DateTime = New DateTime(DateTime.Now.Year, DateTime.Now.Month, DateTime.Now.Day, DateTime.Now.Hour, 0, 0)
Dim p_end_date As OracleParameter = New OracleParameter
p_end_date.OracleDbType = OracleDbType.Date
p_end_date.Value = d_end_date
p_end_date.ParameterName = "toDateParam"
''Setup Datatable, connections and pull data
Dim myDT As New DataTable
Dim Oconn As New OracleConnection(my_CREDS & my_COMMS)
Dim Ods As New DataSet
Dim Ocommand As OracleCommand = New OracleCommand("select " & _
"username as Recipient, " & _
"to_char(CreatedDate,'YYYY-mm-dd HH24:MI:SS') as CREATEDDATE " & _
"from " & _
"tbl.one " & _
"where " & _
"CreatedDate >= :fromDateParam " & _
" and CreatedDate < :toDateParam;", Oconn)
Ocommand.Parameters.Add(p_start_date)
Ocommand.Parameters.Add(p_end_date)
Using Oda As New OracleDataAdapter(Ocommand)
Oda.Fill(myDT)
End Using
Ocommand.Dispose()
这样做会在尝试填充数据表时出错：Oda.Fill(myDT)。谁能解释为什么？我对 Oracle 数据库查询还是很陌生。