① 这种情况下怎么写sql语句超难
用SQL也能实现,只是字段太度。写出来会很麻烦,建议用程序实现,那么SQL中只要用*就可以了。
Select * From
(
Select 分钟序号,
case When 增幅1>0.05 Then 1 Else 0 End+
case When 增幅2>0.05 Then 1 Else 0 End+
case When 增幅3>0.05 Then 1 Else 0 End+…… as 数量
From
(
Select B.分钟序号,abs(B.信号源1 -A.信号源1)*1.0 /A.信号源1 增幅1,abs(B.信号源2 -A.信号源2)*1.0 /A.信号源2 增幅2,……
From 表名 A Inner Join 表名 B On A.分钟序号=B.分钟序号-1
)A
)AA Where 数量>85
语句中的...可以用循环生成。
② 这个sql语句该如何写,请写出完整的sql语句
使用SQL通配符可以替代一个或多个字符,即模糊查询,也就是包含关系。
SQL通配符必须与 LIKE 运算符一起使用。在SQL中,可使用以下通配符如下:
1、% 替代一个或多个字符
2、_ 仅替代一个字符
3、[charlist] 字符列中的任何单一字符
4、[^charlist]或者[!charlist]不在字符列中的任何单一字符
以图中表格为例,说明一下各通配符用法
1、 查询居住在以 "Ne" 开始的城市里的人:
SELECT * FROM PersonsWHERE City LIKE 'Ne%'
2、查询居住在包含 "lond" 的城市里的人:
SELECT * FROM PersonsWHERE City LIKE '%lond%'
3、查询名字的第一个字符之后是 "eorge" 的人:
SELECT * FROM PersonsWHERE FirstName LIKE '_eorge'
4、查询记录的姓氏以 "C" 开头,然后是一个任意字符,然后是 "r",然后是任意字符,然后是 "er":
SELECT * FROM PersonsWHERE LastName LIKE 'C_r_er'
5、查询居住的城市以 "A" 或 "L" 或 "N" 开头的人:
SELECT * FROM PersonsWHERE City LIKE '[ALN]%'
6、查询居住的城市不以"A" 或 "L" 或 "N" 开头的人:
SELECT * FROM PersonsWHERE City LIKE '[!ALN]%'
③ 请根据下面的要求写出sql语句
select name,count(sj),gh from table group by name,gh
④ sql如何删除重复数据
sql查询去除重复值语句
sql 单表/多表查询去除重复记录
单表distinct
多表group by
group by 必须放在 order by 和 limit之前,不然会报错
************************************************************************************
1、查找表中多余的重复记录,重复记录是根据单个字段(peopleId)来判断
select * from people
where peopleId in (select peopleId from people group by peopleId having count(peopleId) > 1)
2、删除表中多余的重复记录,重复记录是根据单个字段(peopleId)来判断,只留有rowid最小的记录
delete from people
where peopleId in (select peopleId from people group by peopleId having count(peopleId) > 1)
and rowid not in (select min(rowid) from people group by peopleId having count(peopleId )>1)
3、查找表中多余的重复记录(多个字段)
select * from vitae a
where (a.peopleId,a.seq) in (select peopleId,seq from vitae group by peopleId,seq having count(*) > 1)
4、删除表中多余的重复记录(多个字段),只留有rowid最小的记录
delete from vitae a
where (a.peopleId,a.seq) in (select peopleId,seq from vitae group by peopleId,seq having count(*) > 1)
and rowid not in (select min(rowid) from vitae group by peopleId,seq having count(*)>1)
5、查找表中多余的重复记录(多个字段),不包含rowid最小的记录
select * from vitae a
where (a.peopleId,a.seq) in (select peopleId,seq from vitae group by peopleId,seq having count(*) > 1)
and rowid not in (select min(rowid) from vitae group by peopleId,seq having count(*)>