Expected one result (or null) to be returned by selectOne(), but found: 2
1 "C:\Program Files\Java\jdk1.8.0_91\bin\java.exe" -javaagent:D:\ruanjian\softwareInstall\TechnicalSoftware\idea\lib\idea_rt.jar=61413:D:\ruanjian\softwareInstall\TechnicalSoftware\idea\bin -Dfile.encoding=UTF-8 -classpath "C:\Program Files\Java\jdk1.8.0_91\jre\lib\charsets.jar;C:\Program Files\Java\jdk1.8.0_91\jre\lib\deploy.jar;C:\Program Files\Java\jdk1.8.0_91\jre\lib\ext\access-bridge-64.jar;C:\Program Files\Java\jdk1.8.0_91\jre\lib\ext\cldrdata.jar;C:\Program Files\Java\jdk1.8.0_91\jre\lib\ext\dnsns.jar;C:\Program Files\Java\jdk1.8.0_91\jre\lib\ext\jaccess.jar;C:\Program Files\Java\jdk1.8.0_91\jre\lib\ext\jfxrt.jar;C:\Program Files\Java\jdk1.8.0_91\jre\lib\ext\localedata.jar;C:\Program Files\Java\jdk1.8.0_91\jre\lib\ext\nashorn.jar;C:\Program Files\Java\jdk1.8.0_91\jre\lib\ext\sunec.jar;C:\Program Files\Java\jdk1.8.0_91\jre\lib\ext\sunjce_provider.jar;C:\Program Files\Java\jdk1.8.0_91\jre\lib\ext\sunmscapi.jar;C:\Program Files\Java\jdk1.8.0_91\jre\lib\ext\sunpkcs11.jar;C:\Program Files\Java\jdk1.8.0_91\jre\lib\ext\zipfs.jar;C:\Program Files\Java\jdk1.8.0_91\jre\lib\javaws.jar;C:\Program Files\Java\jdk1.8.0_91\jre\lib\jce.jar;C:\Program Files\Java\jdk1.8.0_91\jre\lib\jfr.jar;C:\Program Files\Java\jdk1.8.0_91\jre\lib\jfxswt.jar;C:\Program Files\Java\jdk1.8.0_91\jre\lib\jsse.jar;C:\Program Files\Java\jdk1.8.0_91\jre\lib\management-agent.jar;C:\Program Files\Java\jdk1.8.0_91\jre\lib\plugin.jar;C:\Program Files\Java\jdk1.8.0_91\jre\lib\resources.jar;C:\Program Files\Java\jdk1.8.0_91\jre\lib\rt.jar;F:\workspace\test\testMybatis\mybatisTest\target\classes;D:\ruanjian\softwareInstall\TechnicalSoftware\repository\lib\org\mybatis\mybatis\3.3.0\mybatis-3.3.0.jar;D:\ruanjian\softwareInstall\TechnicalSoftware\repository\lib\mysql\mysql-connector-java\8.0.16\mysql-connector-java-8.0.16.jar;D:\ruanjian\softwareInstall\TechnicalSoftware\repository\lib\com\google\protobuf\protobuf-java\3.6.1\protobuf-java-3.6.1.jar;D:\ruanjian\softwareInstall\TechnicalSoftware\repository\lib\log4j\log4j\1.2.17\log4j-1.2.17.jar;D:\ruanjian\softwareInstall\TechnicalSoftware\repository\lib\org\slf4j\slf4j-api\1.7.30\slf4j-api-1.7.30.jar;D:\ruanjian\softwareInstall\TechnicalSoftware\repository\lib\org\slf4j\slf4j-log4j12\1.7.7\slf4j-log4j12-1.7.7.jar" com.lenovo.MybatisExample 2 DEBUG 2022-03-11 16:54:29,833 org.apache.ibatis.logging.LogFactory: Logging initialized using 'class org.apache.ibatis.logging.slf4j.Slf4jImpl' adapter. 3 DEBUG 2022-03-11 16:54:30,018 org.apache.ibatis.datasource.pooled.PooledDataSource: PooledDataSource forcefully closed/removed all connections. 4 DEBUG 2022-03-11 16:54:30,020 org.apache.ibatis.datasource.pooled.PooledDataSource: PooledDataSource forcefully closed/removed all connections. 5 DEBUG 2022-03-11 16:54:30,020 org.apache.ibatis.datasource.pooled.PooledDataSource: PooledDataSource forcefully closed/removed all connections. 6 DEBUG 2022-03-11 16:54:30,020 org.apache.ibatis.datasource.pooled.PooledDataSource: PooledDataSource forcefully closed/removed all connections. 7 DEBUG 2022-03-11 16:54:30,180 org.apache.ibatis.transaction.jdbc.JdbcTransaction: Opening JDBC Connection 8 DEBUG 2022-03-11 16:54:30,388 org.apache.ibatis.datasource.pooled.PooledDataSource: Created connection 1295226194. 9 DEBUG 2022-03-11 16:54:30,388 org.apache.ibatis.transaction.jdbc.JdbcTransaction: Setting autocommit to false on JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@4d339552] 10 DEBUG 2022-03-11 16:54:30,393 org.apache.ibatis.logging.jdbc.BaseJdbcLogger: ==> Preparing: select id,role_name,note from t_role where 1=1 11 DEBUG 2022-03-11 16:54:30,466 org.apache.ibatis.logging.jdbc.BaseJdbcLogger: ==> Parameters: 12 DEBUG 2022-03-11 16:54:30,508 org.apache.ibatis.logging.jdbc.BaseJdbcLogger: <== Total: 2 13 Exception in thread "main" org.apache.ibatis.exceptions.TooManyResultsException: Expected one result (or null) to be returned by selectOne(), but found: 2 14 at org.apache.ibatis.session.defaults.DefaultSqlSession.selectOne(DefaultSqlSession.java:77) 15 at org.apache.ibatis.binding.MapperMethod.execute(MapperMethod.java:69) 16 at org.apache.ibatis.binding.MapperProxy.invoke(MapperProxy.java:53) 17 at com.sun.proxy.$Proxy0.findRole(Unknown Source) 18 at com.lenovo.MybatisExample.main(MybatisExample.java:16) 19 20 Process finished with exit code 1
这个错误是因为查询到的结果集中含有2个角色对象，应该用List来接收，但是实际使用Role对象接收的，导致报错
