报错BUG汇总ResultsException: Expected one result (or null) to be returned by selectOne(), but found: 3

完整报错信息:

nested exception is org.apache.ibatis.exceptions.TooManyResultsException: Expected one result (or null) to be returned by selectOne(), but found: 
 
	at org.mybatis.spring.MyBatisExceptionTranslator.translateExceptionIfPossible(MyBatisExceptionTranslator.java:76) ~[mybatis-spring-1.2.3.jar:1.2.3]
	
	at org.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:399) ~[mybatis-spring-1.2.3.jar:1.2.3]
	at com.sun.proxy.$Proxy10.selectOne(Unknown Source) ~[na:na]
	at org.mybatis.spring.SqlSessionTemplate.selectOne(SqlSessionTemplate.java:165) ~[mybatis-spring-1.2.3.jar:1.2.3]
	at org.apache.ibatis.binding.MapperMethod.execute(MapperMethod.java:69) ~[mybatis-3.3.0.jar:3.3.0]
	at org.apache.ibatis.binding.MapperProxy.invoke(MapperProxy.java:53) ~[mybatis-3.3.0.jar:3.3.0]
	at com.sun.proxy.$Proxy49.selectByPrimaryKey(Unknown Source) ~[na:na]
	
	Caused by: org.apache.ibatis.exceptions.TooManyResultsException: Expected one result (or null) to be returned by selectOne(), but found: 3
	at org.apache.ibatis.session.defaults.DefaultSqlSession.selectOne(DefaultSqlSession.java:77) ~[mybatis-3.3.0.jar:3.3.0]
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.7.0_79]
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) ~[na:1.7.0_79]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.7.0_79]
	at java.lang.reflect.Method.invoke(Method.java:606) ~[na:1.7.0_79]
	at org.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:386) ~[mybatis-spring-1.2.3.jar:1.2.3]
	... 35 common frames omitted

错误分析:

selectOne(), but found: 3；这一句理解就是在查询的时候你查询的是一个，但是数据有三条，然后mybatis抛出的异常信息,简单话理解就是:

这种就是查询到了三条数据，返回的是一个实体并不是一个List多条数据

解决方案:
在你的mapper接口中:

 //flowHolidayNumberPojo queryTeacherFlowNumber(@Param("userId")String userId);
    //改成这个
    List<flowHolidayNumberPojo> queryTeacherFlowNumber(@Param("userId")String userId);