[.NET] Oracle Client Exception
<div id="cnblogs_post_body">最近的项目使用Oracle DB。在.NET里可以使用Oracle Client，来对Oracle DB下SQL指令。写了下面的程序代码，用来取得User数据表里的User数据。using (OracleConnection connection = new OracleConnection(connectionString)){ connection.Open(); using (OracleCommand command = new OracleCommand()) { command.Connection = connection; command.Parameters.Add(":lastName", "Chou"); command.Parameters.Add(":firstName", "Clark"); command.CommandText = @"SELECT * FROM USER_DATA WHERE FIRST_NAME=:firstName AND LAST_NAME=:lastName"; using (OracleDataReader reader = command.ExecuteReader()) { while (reader.Read()) { // XXXXXXX } connection.Close(); } }}
快速打完、按下执行。却产生了让人摸不清头绪的错误例外「ORA-01722:无效的数字」。
http://Files.Dotblogs.com.tw/clark/1207/2012713132435874.png
搞了半天才发现使用OracleCommand.Parameters来加参数是有顺序性的。在OracleCommand.CommandText里参数出现的顺序，必须要和OracleCommand.Parameters是一致的。也就是下列的程序代码才能正常执行：
using (OracleConnection connection = new OracleConnection(connectionString)){ connection.Open(); using (OracleCommand command = new OracleCommand()) { command.Connection = connection; command.Parameters.Add(":firstName", "Clark"); command.Parameters.Add(":lastName", "Chou"); command.CommandText = @"SELECT * FROM USER_DATA WHERE FIRST_NAME=:firstName AND LAST_NAME=:lastName"; using (OracleDataReader reader = command.ExecuteReader()) { while (reader.Read()) { // XXXXXXX } connection.Close(); } }}
在网络上与朋友讨论这个问题与解法。经由Demo的提点，才知道原来只要将OracleCommand.BindByName设定为True就可以解决这个问题。范例程序如下：
using (OracleConnection connection = new OracleConnection(connectionString)){ connection.Open(); using (OracleCommand command = new OracleCommand()) { command.BindByName = true; command.Connection = connection; command.Parameters.Add(":lastName", "Chou"); command.Parameters.Add(":firstName", "Clark"); command.CommandText = @"SELECT * FROM USER_DATA WHERE FIRST_NAME=:firstName AND LAST_NAME=:lastName"; using (OracleDataReader reader = command.ExecuteReader()) { while (reader.Read()) { // XXXXXXX } connection.Close(); } }}
趁还有印象快速纪录一篇下来，为自己做个纪录，也希望能帮助到有需要的开发人员。 当然也要再次感谢Demo大大。:D
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