sql求和出现null时赋值为0

今天在实现签到功能的时候，测试用了没有签到过的用户id，所以在查询总积分的过程中出现了积分为空值的异常，进过修改，将其签到积分的空值改为0值然后再存入Model中程序正常运行。

sql求和出现null时赋值为0：

语句为：

SELECT 
CASE 
	WHEN sumScore IS NULL THEN 0 
	ELSE sumScore 
END AS sumScore 
FROM(
	SELECT SUM(poi_score)AS sumScore 
	FROM points WHERE u_id = 9 AND poi_del = 0
	) 
AS a

查询当前用户签到总积分Service：

public SumModel sumScores(UserModel user){
		sql = "SELECT CASE WHEN sumScore IS NULL THEN 0 ELSE sumScore END AS sumScore FROM(SELECT SUM(poi_score)AS sumScore FROM points WHERE u_id = ? AND poi_del = ?) AS a";
		data = db.query(sql, user.getU_id(),0);
		return mapToSumScoreModel(data).get(0);
	}

泛型转换：

public List<SumModel> mapToSumScoreModel(List<Map<String,Object>> data){
			List<SumModel> list = new ArrayList<>();
			SumModel sumModel = null;
			for (Map<String,Object> map : data) {
				sumModel = new SumModel(
						Integer.parseInt(map.getOrDefault("sumScore", "").toString()));
				list.add(sumModel);
			}
			return list;
		}