org.springframework.dao.EmptyResultDataAccessException: Incorrect result size: expected 1, actual 0-优快云博客

org.springframework.dao.IncorrectResultSizeDataAccessException: Incorrect result size: expected 1, actual 0

spring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 = 2
null result: select max(salary) from user where 1 = 2 返回就是null

0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
以上内容转载自：

http://www.cnblogs.com/ufoer23/archive/2005/11/29/286682.html

具体解决方法：使用如下方法

List<Program> programList = getJdbcTemplate().query(query_sql,
    args, new RowMapper() {
     public Object mapRow(ResultSet rs, int num)
       throws SQLException {
      Program program = new Program();
      ......

      return program;
     }
    });
if(programList!=null &&programList.size()>0){
   program = programList.get(0);
}else {
   program = null;
}

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