INCORRECT RESULT SIZE: EXPECTED 1, ACTUAL 0错误以及解决方法

Posted 2023-01-06 tfy1332

INCORRECT RESULT SIZE: EXPECTED 1, ACTUAL 0错误以及解决方法

错误如下：org.springframework.dao.IncorrectResultSizeDataAccessException: Incorrect result size: expected 1, actual 0spring的javadoc上讲getObject(String, Object[], Class) will return NULL if the result of the query is NUL这里有0行和nullresult的区别0行: select salary from user where 1 = 2null result: select max(salary) from user where 1 = 2 返回就是null0行一定抛出IncorrectResultSizeDataAccessException异常原因如下ResultSetMetaData rsmd = rs.getMetaData();int nrOfColumns = rsmd.getColumnCount();这里返回ResultSet的列数 if (nrOfColumns != 1) throw new IncorrectResultSizeDataAccessException( "Expected single column but found " + nrOfColumns, 1, nrOfColumns); 0行,多于1行,就抛异常了 最好还是用QueryForList,返回的list的size为0,就是0行