Winform 利用 Oracle.ManagedDataAccess访问Oracle数据库时出现以下错误：
Message = "每个配置文件中只允许存在一个 <configSections> 元素，并且，如果存在该元素，它还必须是根 <configuration> 元素的第一个子元素。
出现以上错误时，需调整app.config中配置节点，将configSections的节点放在第一个子元素，入一下配置文件
<?xml version="1.0" encoding="utf-8"?>
<configuration>
<configSections>
<section name="oracle.manageddataaccess.client"
type="OracleInternal.Common.ODPMSectionHandler, Oracle.ManagedDataAccess, Version=4.122.18.3, Culture=neutral, PublicKeyToken=89b483f429c47342"/>
<section name="log4net" type="System.Configuration.IgnoreSectionHandler"/>
</configSections>
<startup>
<supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.0"/>
</startup>
<log4net>
<root>
<appender-ref ref="LogFileAppender"/>
</root>
<appender name="LogFileAppender" type="log4net.Appender.RollingFileAppender">
<file value="./log/log4netfile.txt"/>
<appendToFile value="true"/>
<rollingStyle value="Date"/>
<LockingModel type="log4net.Appender.FileAppender+MinimalLock, log4net"/>
<datePattern value="yyyyMMdd-HH:mm:ss"/>
<layout type="log4net.Layout.PatternLayout">
<param name="ConversionPattern" value="%d [%t] %-5p %c [%x] %X{auth} - Line:%L %m%n"/>
</layout>
</appender>
</log4net>
<system.data>
<DbProviderFactories>
<remove invariant="Oracle.ManagedDataAccess.Client"/>
<add name="ODP.NET, Managed Driver" invariant="Oracle.ManagedDataAccess.Client" description="Oracle Data Provider for .NET, Managed Driver"
type="Oracle.ManagedDataAccess.Client.OracleClientFactory, Oracle.ManagedDataAccess, Version=4.122.18.3, Culture=neutral, PublicKeyToken=89b483f429c47342"/>
</DbProviderFactories>
</system.data>
<runtime>
<assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
<dependentAssembly>
<publisherPolicy apply="no"/>
<assemblyIdentity name="Oracle.ManagedDataAccess" publicKeyToken="89b483f429c47342" culture="neutral"/>
<bindingRedirect oldVersion="4.122.0.0 - 4.65535.65535.65535" newVersion="4.122.18.3"/>
</dependentAssembly>
</assemblyBinding>
</runtime>
<oracle.manageddataaccess.client>
<version number="*">
<dataSources>
<dataSource alias="SampleDataSource" descriptor="(DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=localhost)(PORT=1521))(CONNECT_DATA=(SERVICE_NAME=ORCL))) "/>
</dataSources>
</version>
</oracle.manageddataaccess.client>
</configuration>