sql server 1

use ChargeDB;
--更新数据
update dbo.SF_JLB set SF_YSZJE='150',SF_SSZJE='150' where SF_SSZJE='345' and SF_SFRQ>='2023/8/1' and SF_SFRQ<='2023/8/19 23:59:59';
--查询转换求和
select SUM(convert(float,SF_SSZJE)) from dbo.SF_JLB where SF_SFRQ>='2023/7/1' and SF_SFRQ<='2023/7/31 23:59:59' and SF_Flag='0';
--分号结束SQL语句
select * from SF_JLB;
--分组聚合
select sf_hphm,
COUNT(*) as 次数
from SF_JLB group by SF_HPHM;--按号牌分组关统计每个号牌开站以来来站检测次数
--从查询中查询,注意(...) as t
select * from (select * from SF_JGBZ) as t;
--分组 聚合
select sf_hphm,
COUNT(*) as 次数
from SF_JLB group by SF_HPHM;--按号牌分组关统计每个号牌开站以来来站检测次数
--分组 聚合 从查询中查询
select sf_hphm,次数,
case
when 次数>=4 then '优秀'
when 次数>=3 then '中上'
when 次数>=2 then '中等'
when 次数>=1 then '普通'
end AS grade
from
(select sf_hphm,
COUNT(*) as 次数
from SF_JLB group by SF_HPHM) as t;