完成 DB2 与 .NET 框架的无缝接口
毛病检讨
在本节中，您将学习若何应用 ADO.NET 应用顺序的毛病检讨器材。 您将窥察应用 Exception 器材和 DB2 .NET 跟踪及 DB2 跟踪实用顺序举行底子的错误处理惩罚和呈文。
错误处理惩罚
如果在 ADO.NET 中实行准确的错误处理惩罚要领，在 ADO.NET 应用顺序中，应该将逻辑包括在 try/catch 块中。当 ADO.NET 要领中泛起错误时，将抛出 Exception 器材。因而， 对付包括数据库操作的每个 try 块，响应的 catch 块应该包括处理惩罚一个 Exception 器材的逻辑。
在清单 10 中的示例中，一个 SELECT 语句中的 WHERE 子句含有标准不兼容的操作数：STAFF 表的 JOB 列的数据标准是 VARCHAR，而不是 INTEGER。
清单 10. try catch 块
try
{
...
cmd.Transaction = trans;
cmd.CommandText = "SELECT ID, NAME FROM STAFF WHERE JOB = 99";
reader = cmd.ExecuteReader();
...
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
}
当 try 块中泛起一个非常时，catch 块将捕获该非常。
ex.Message 包括非常的内容。含不兼容操作数的 SELECT 语句会生成以下非常：
ERROR [42818] [IBM][DB2/NT] SQL0401N The data types of the operands for the operation "=" are not compatible. SQLSTATE=42818
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DB2 ADO.NET 跟踪
为了调试 DB2 ADO.NET 应用顺序，可以应用 DB2 ADO.NET 跟踪实用顺序。 要激活 ADO.NET 跟踪实用顺序，可以设置以下环境变量：
SET DB2NMPTRACE=1
激活 ADO.NET 跟踪实用顺序之后，每当运转一个 DB2 ADO.NET 应用顺序，就会生成对 ADO.NET 挪用的一个具体的跟踪。清单 11 展示了后面开辟的 AccessSamplDb 应用顺序生成的跟踪数据：
清单 11. .NET 跟踪示例
| DB2Trace.TraceVersion fnc data 10: Version: 9.0.0.1 | DB2Trace.TraceVersion fnc data 11: Framework: 1.1.4322.2300 | DB2Interop.Init fnc entry | | DB2Interop.Init fnc data 10: file:///c:/windows/assembly/gac/ibm.data.db2/9.0.0.1 __7c307b91aa13d208/ibm.data.db2.dll | | DB2Interop.Init fnc data 19: 9.1.0.DEF.1 | | DB2Interop.Init fnc data 20: DB2COPY1 | | DB2Interop.Init fnc data 30: D:\IBM\SQLLIB\ | | DB2Interop.Init fnc data 50: D:\IBM\SQLLIB\\bin\db2app.dll | | DB2Interop.Init fnc data 55: a | | DB2Interop.Init fnc data 60: 15 | | DB2Interop.Init fnc data 97: SOFTWARE\IBM\DB2\InstalledCopies | | DB2Interop.Init fnc data 98: DB2COPY1 | | DB2Interop.Init fnc data 99: 0 | DB2Interop.Init fnc exit2, rc = 0 - False, 15 db2trace False | DB2ConnPool.GetDB2ConnPool fnc data 5: 0 | DB2ConnPool.GetDB2ConnPool fnc data 10: 1 | DB2ConnPool.GetDB2ConnPool fnc data 11: 55706604 | DB2ConnPool.GetDB2ConnPool fnc data 254: 1 1 DB2ConnPool.GetDB2ConnPool fnc exit, rc = 0 DB2ConnPool.DB2ConnPool fnc exit, rc = 0 DB2Connection.DB2Connection1 fnc entry | DBCWrapper.DBCWrapper fnc entry | DBCWrapper.DBCWrapper fnc exit, rc = 0 | DB2Connection.ConnectionString.set fnc entry1 - Database=SAMPLE | | DB2Connection.State.get fnc entry | | | DB2Connection.State.get api data 10: Closed | | DB2Connection.State.get fnc exit, rc = 0 | | DB2ConnPool.ReplaceConnectionStringParms fnc entry | | | DB2ConnPool.ReplaceConnectionStringParms fnc data 10: Database=SAMPLE | | | DB2ConnPool.ReplaceConnectionStringParms fnc data 15: database, SAMPLE | | | DB2ConnPool.ReplaceConnectionStringParms fnc data 20: dsn=SAMPLE; | | DB2ConnPool.ReplaceConnectionStringParms fnc exit, rc = 0 | DB2Connection.ConnectionString.set fnc exit, rc = 0 DB2Connection.DB2Connection1 fnc exit, rc = 0 DB2Connection.Open fnc entry | DB2Connection.State.get fnc entry | | DB2Connection.State.get api data 10: Closed | DB2Connection.State.get fnc exit, rc = 0 | DB2ConnPool.GetDB2ConnPool fnc entry | | DB2ConnPool.GetDB2ConnPool fnc data 254: 1 2 | DB2ConnPool.GetDB2ConnPool fnc exit, rc = 0
当具有含不兼容操作数的 SELECT 语句的顺序运转时， .NET 跟踪实用顺序捕获到错误：
清单 12. .NET 跟踪实用顺序捕获到的错误
DB2Command.ExecuteReader2 fnc exit, rc = 0 DB2ConnPool.CheckClose fnc entry DB2Exception.Message.get fnc entry | DB2ConnPool.CheckClose fnc data 10: 2/8/2007 4:14:39 PM | | DB2Resource.DB2Resource fnc entry2 - db2nmp.xml, null | | DB2ConnPoolWrapper.LockPool fnc entry | | | DB2Resource.GetMsgPath fnc entry | | | | DB2ConnPoolWrapper.LockPool fnc data 10: dsn=SAMPLE; | | | | | DB2Resource.GetMsgPath fnc data 10: D:\IBM\SQLLIB\ | | | | DB2ConnPoolWrapper.LockPool fnc exit, rc = 0 | | | DB2Resource.GetMsgPath fnc exit1, rc = 0 - D:\IBM\SQLLIB\msg\en_US | | | DB2ConnPool.CheckClose fnc data 20: dsn=SAMPLE;, xa: False, conns: 1, free: 0 | | DB2Resource.DB2Resource fnc exit, rc = 0 | | DB2ConnPool.CheckClose fnc data 25: POOL [dsn=SAMPLE;] 1->NULL pPool.pLastConn = 1 | | DB2Exception.Message.get fnc data 20: ERROR [42818] [IBM][DB2/NT] SQL0401N The d ata types of the operands for the operation "=" are not compatible. SQLSTATE=42818 | | DB2ConnPool.CheckClose fnc data 30: dbc: 1, xa: False, inuse: True, free on close: False, lifetime: -1, 0 | DB2Exception.Message.get fnc exit, rc = 0 | DB2ConnPoolWrapper.UnlockPool fnc entry ERROR [42818] [IBM][DB2/NT] SQL0401N The data types of the operands for the operatio n "=" are not compatible. SQLSTATE=42818
DB2 .NET Provider 应用 DB2 CLI 的一些组件。这对付 DB2 ADO.NET 应用顺序确定成就无意会很有效，可以获得 CLI 和 DB2 跟踪信息。
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