檢查完xml檔案沒錯後，還是出現錯誤

org.mybatis.spring.MyBatisSystemException: nested exception is org.apache.ibatis.binding.BindingException: Parameter 'outTradeNo' not found. Available parameters are [video_order, param1]
	at org.mybatis.spring.MyBatisExceptionTranslator.translateExceptionIfPossible(MyBatisExceptionTranslator.java:92) ~[mybatis-spring-2.0.4.jar:2.0.4]
	at org.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:440) ~[mybatis-spring-2.0.4.jar:2.0.4]
	at com.sun.proxy.$Proxy62.insert(Unknown Source) ~[na:na]
	at org.mybatis.spring.SqlSessionTemplate.insert(SqlSessionTemplate.java:271) ~[mybatis-spring-2.0.4.jar:2.0.4]
	at org.apache.ibatis.binding.MapperMethod.execute(MapperMethod.java:62) ~[mybatis-3.5.4.jar:3.5.4]
	at org.apache.ibatis.binding.MapperProxy$PlainMethodInvoker.invoke(MapperProxy.java:144) ~[mybatis-3.5.4.jar:3.5.4]
	at org.apache.ibatis.binding.MapperProxy.invoke(MapperProxy.java:85) ~[mybatis-3.5.4.jar:3.5.4]
	at com.sun.proxy.$Proxy65.saveOrder(Unknown Source) ~[na:na]
	at net.xdclass.online_xdclass.service.impl.VideoOrderServiceImpl.save(VideoOrderServiceImpl.java:53) ~[classes/:na]
	at net.xdclass.online_xdclass.controller.VideoOrderController.saveOrder(VideoOrderController.java:30) ~[classes/:na]
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_241]
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_241]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_241]
	at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_241]
	at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:190) ~[spring-web-5.2.5.RELEASE.jar:5.2.5.RELEASE]
	at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:138) ~[spring-web-5.2.5.RELEASE.jar:5.2.5.RELEASE]
	at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:105) ~[spring-webmvc-5.2.5.RELEASE.jar:5.2.5.RELEASE]
	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:879) ~[spring-webmvc-5.2.5.RELEASE.jar:5.2.5.RELEASE]
	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapte
 

mapper裡程式碼

int saveOrder(@Param("video_order") VideoOrder videoOrder);

去掉別名後

int saveOrder(VideoOrder videoOrder);

再次執行，執行成功。

結論：

如果mapper執行的是查詢操作，引數都需要（一個引數時可以不加）加別名。
如果執行的是插入操作，引數不需加別名（可能和xml裡不是直接呼叫引數，而是呼叫引數物件裡的屬性有關）。