11.18 学习
1.sql
select m.user_id,round(ifnull(cfnum/p,0),2) confimation_rate from (select a.user_id,ifnull(num,0) p from Signups a left join (select user_id,count(*) num from Confirmations group by user_id)b on a.user_id=b.user_id) m left join(select user_id,count(*)cfnum from Confirmations where action='confirmed' group by user_id) non m.user_id=n.user_id;
2.try catch
@Overridepublic R<ModelCenterVO> fetchByModelCode(String modelCode) {try {result=....one();return R.ok(result);} catch (TooManyResultsException e) {log.error("查询到多个结果,错误类型={},错误信息={}",e.getClass().getName(),e.getMessage());return R.fail("modelCode查询到多个模型");} catch (Exception e) {log.error("内部错误,错误类型={},错误信息={}",e.getClass().getName(),e.getMessage());return R.fail("内部错误");}}
