用 UNION 联合查询(select * from 表名 where 字段名 = '1' limit 5 ) union(select * from 表名 where 字段名 = '2' limit 5 )
选择时(visittime)的时间,金额(大小写状态时,= 1,那么1,否则为0结束)状态1,总和(案件时状态= 2,那么1,否则为0结束)状态2,总和(案件时状态= 3,那么1,否则为0结束)STATE3 from表名where日期= 7(使用变量代替) 按小时(visittime) 组---- 其中提取物(每天从visittime)= 7
参考sql语句select sum(case when a1=1 then 1 else 0 end )as a1count,sum(case when a2=1 then 1 else 0 end )as a2count,sum(case when a3=1 then 1 else 0 end )as a3count,sum(case when a4=1 then 1 else 0 end )as a4countfrom 表
IF i尝敞佰缎脂等拌劝饱滑 = 3 THEN set i=i+3; ELSEIF i = 4 THEN set i=i+4; ELSE set i=i+5; END IF; case i = 3 then set i=i+3; case i = 4 then set i=i+4; end
好像不清楚
select hour(visittime) 时间,sum(case when state=1 then 1 else 0 end) state1,sum(case when state=2 then 1 else 0 end) state2,sum(case when state=3 then 1 else 0 end) state3from table where 日期=7号(用变量代替)group by hour(visittime) ----where extract(day from visittime)=7
一使用select子句进行多表查询select 字段名 from 表1,表2 … where 表1.字段 = 表2.字段 and 其它查询条件select a.id,a.name,a.address,a.date,b.math,b.english,b.chinese from tb_demo065_tel as b,tb_demo065 as a where a.id=b.id注:在上面的
你好!不太好处理.话说你这是sql习题还是实际网站应用的问题?你试试看语句SELECT uid,COUNT(*) FROM 表1 GROUP BY uid,LEFT(time,8);我也不确定能行我的回答你还满意吗~~
错误方法:select * from A where age=(select max(age) from A where sex=＂男＂) or age=(select max(age) from A where sex=＂女＂) 解释:先用两个子查询分别把男女生中年龄最大的数字筛选出来,然后在整个表中寻找对应年龄的男生与女
order by cont ->order by count(*)select count(*) as cont,ctt_id from tmp group by ctt_id order by count(*) desc limit 0,20