【SQL Server】常用Code及练习题
数据库练习
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0.常用CHECK CODE
(1). 查看不同库表间的依赖关系
select distinct name
from sysobjects(nolock) o, syscomments(nolock) s
where o.id = s.id
and text like '%COFIS_STG_GCAP_PC_APPLICATION_DELTA%'
and o.xtype = 'P'
order by name
select distinct object_name(id)
from syscomments
where id in (select id from sysobjects where type in('V','P')) --V表示视图，P表示存储过程
and text like '%ODS_BUSINESS_PORTFOLIO_REPORT_DM_ETL%'--tablename为需要查询被引用的表名称
(2). 查找某个字段在哪张表里
select [name]
from [库名].[dbo].sysobjects
where id in(
select id
from [库名].[dbo].syscolumns
Where name='字段名'
)
--多个字段
select [name]
from [ODS].[dbo].sysobjects
where id in(
--select id
--from [ODS].[dbo].syscolumns
--Where name='Contract_No'
--InterSect--交集
--Except--差集
--Union--并集
select id
from [ODS].[dbo].syscolumns
Where name='Applicant_Name'
)
(3). 查看pro在不在用
SELECT * FROM msdb.dbo.sysjobs JOB WITH( NOLOCK)
INNER JOIN msdb. dbo.sysjobsteps STP WITH(NOLOCK )
ON STP .job_id = JOB .job_id WHERE
STP .command LIKE '%P_ETL_CMS_ODS_CONTRACT%'
(4). 模糊查表名
select name
from sys.objects
where type='U' and name like '%date%';
(5). 查看存储过程在哪些作业中被调用
SELECT *
FROM msdb.dbo.sysjobs JOB WITH( NOLOCK)
INNER JOIN msdb. dbo.sysjobsteps STP WITH(NOLOCK )
ON STP .job_id = JOB .job_id
WHERE STP .command LIKE N'%PROC_COLLECTIONS_DATA%'
(6). 查询存储过程和视图是否用到表
select distinct object_name(id) from syscomments
where id in (
select id
from sysobjects
where type in('V','P','U')
) --V表示视图，P表示存储过程，'U'用户表
and text like '%BP_MAIN%'--tablename为需要查询被引用的表名称
(7). 查询存储过程和视图是否用到表字段
--查询存储过程视图是否用到表和字段
select name from sysobjects as s
inner join syscomments as o
on s.id=o.id
where text like N'%表名%字段名%'
(8). 快速比较两个张，相同和不同的数据！
--不同数据
select * from b
except
select * from a
--相同数据
select * from a
intersect
select * from b
(9). 查看某个proc的执行时间记录
SELECT TOP 100 db_name(d.database_id) as DBName,
s.name as 存储名称,
s.type_desc as 存储类型,
d.cached_time as SP添加到缓存的时间,
d.last_execution_time as 上次执行SP的时间,
d.last_elapsed_time as [上次执行SP所用的时间（微妙）],
d.total_elapsed_time as [完成此SP的执行所用的总时间（微妙）],
d.total_elapsed_time/d.execution_count as [平均执行时间（微妙）],
d.execution_count as 自上次编译以来所执行的次数
FROM SYS.procedures S JOIN SYS.dm_exec_procedure_stats D
ON S.object_id=D.object_id
WHERE S.NAME='P_COFIS_STG_PBOC_CORP_CAPTOWN_FULL'
ORDER BY D.total_elapsed_time/D.execution_count DESC
(10). 查看存储过程在哪些作业中被调用
SELECT description,last_run_date,last_run_time,*
FROM msdb.dbo.sysjobs JOB WITH( NOLOCK)
INNER JOIN msdb. dbo.sysjobsteps STP WITH(NOLOCK )
ON STP .job_id = JOB .job_id
WHERE STP .command LIKE N'%SP_Business_Portfolio_Report_DM%'
(11). 查看表的主键
1)利用SQL自带的存储过程找到SqlServer主键
EXEC sp_pkeys @table_name='表名'
2)利用系统表INFORMATION_SCHEMA.KEY_COLUMN_USAGE 找到SqlServer主键
SELECT TABLE_NAME,COLUMN_NAME
FROM INFORMATION_SCHEMA.KEY_COLUMN_USAGE
WHERE TABLE_NAME='CONTRACT_ASSET_COLLATERAL_R'
(12).保留小数
1)cast 字段 as float --(保留两位小数)
2)ROUND(字段,2)
(13).限制工作日 T+1
Convert(datetime,Convert(VARCHAR,[时间字段],112)) >= Convert(datetime,Convert(VARCHAR,CASE WHEN Datepart(dw,Getdate()) = 2 THEN Getdate() - 3 ELSE Getdate() - 1 END,112))
(14).Check DB 磁盘空间
WITH DB_Disk_Space
AS (
SELECT
Team = SUBSTRING( 'NONPROD01',0,len('NONPROD01')-1)
,Instance = @@SERVERNAME
,database_name = DB_NAME(database_id)
, log_size_mb = CAST(SUM(CASE WHEN type_desc = 'LOG' THEN size END) * 8.0 / 1024 AS DECIMAL(25,2))
, row_size_mb = CAST(SUM(CASE WHEN type_desc = 'ROWS' THEN size END) * 8.0 / 1024 AS DECIMAL(25,2))
, total_size_GB = CAST(SUM(size) * 8.0 / (1024*1024*1024) AS DECIMAL(25,2))
,Check_Date = CONVERT(varchar(100),getdate(),23)
FROM sys.master_files WITH(NOWAIT)
GROUP BY database_id with ROLLUP
)
(15) 零时Fix 数据
IF EXISTS (SELECT 1 FROM COFIS_STAGING.sys.tables WHERE name = 'STG_COFIS_CONTRACT_BP_Temp')
BEGIN
DROP TABLE COFIS_STAGING..STG_COFIS_CONTRACT_BP_Temp
END
select * into COFIS_STAGING..STG_COFIS_CONTRACT_BP_Temp from COFIS_STAGING..STG_COFIS_CONTRACT_BP
update AA
set AA.ETL_PROCESSED_IND='T'
from(
select
CONTRACT_ID,
CB.BUSINESS_PARTNER_ID,
ISNULL(BR.ROLE_CDE, CB.ROLE_CDE) as role_cde,
CB.ETL_PROCESSED_IND,
ROW_NUMBER() over(partition BY CB.CONTRACT_ID,CB.BUSINESS_PARTNER_ID, ISNULL(BR.ROLE_CDE, CB.ROLE_CDE) order by CB.CONTRACT_ID,CB.BUSINESS_PARTNER_ID, ISNULL(BR.ROLE_CDE, CB.ROLE_CDE) ) rowNums
FROM COFIS_STAGING..STG_COFIS_CONTRACT_BP CB
LEFT JOIN ODS_BP_ROLE_CODE BR ON BR.CS_CODE = CB.ROLE_CDE
WHERE ETL_PROCESSED_IND = 'F'
-- and CONTRACT_ID='CN2109020095' and CB.BUSINESS_PARTNER_ID='1595047'
AND NOT EXISTS
(SELECT 1
FROM ODS_CONTRACT_BP A
WHERE A.CONTRACT_ID = CB.CONTRACT_ID
AND A.BUSINESS_PARTNER_ID = CB.BUSINESS_PARTNER_ID
AND A.ROLE_CDE = ISNULL(BR.ROLE_CDE, CB.ROLE_CDE)
)
) AA
where AA.rowNums>1
(16) Restore DB
USE [master]
ALTER DATABASE [ODS] SET SINGLE_USER WITH ROLLBACK IMMEDIATE
RESTORE DATABASE [ODS] FROM DISK = N'\\Path\ODS\ODS_Full_210306.BAK' WITH FILE = 1, NOUNLOAD, REPLACE, STATS = 5
ALTER DATABASE [ODS] SET MULTI_USER
GO
查看Restore进度
SELECT
session_id,
percent_complete,
DATEADD(MILLISECOND,estimated_completion_time,CURRENT_TIMESTAMP) Estimated_finish_time,
(total_elapsed_time/1000)/60 Total_Elapsed_Time_MINS,
DB_NAME(Database_id) Database_Name,
command,sql_handle
FROM sys.dm_exec_requests WHERE session_id=189
(17). BACKUP DB
非压缩
BACKUP DATABASE PBOC_Interface TO DISK ='\\Path\PBOC_Interface_Full_190909.BAK' WITH INIT , COPY_ONLY;
压缩
BACKUP DATABASE COFIS_Staging TO DISK ='\\Path\COFIS_Staging_210924.BAK' WITH RETAINDAYS = 15, FORMAT, compression, maxtransfersize = 1048576, NAME = 'COFIS_Staging', SKIP, NOREWIND, NOUNLOAD, STATS = 10,COPY_ONLY;
declare @File_name_BAK varchar(200)
declare @Backup_date varchar(200)
declare @Back_Path varchar(200)
select @Backup_date = CONVERT(varchar(200), CAST(GETDATE() AS DATE), 12)
set @Back_Path = '\\SFCN0195\Path\Dragon\'
set @File_name_BAK = @Back_Path + 'GCAP_Full_'+@Backup_date + '.BAK'
begin
--print @File_name_BAK
BACKUP DATABASE DB_NAME TO DISK = @File_name_BAK WITH RETAINDAYS = 15, FORMAT, compression, maxtransfersize = 1048576, NAME = 'DB_NAME', SKIP, NOREWIND, NOUNLOAD, STATS = 10,COPY_ONLY;
end
(18). 按照分隔符“|”,将一行数据转成多行
--Old
select REJECTION_COMMENTS
from APPLICATION_COMMENTS_R
where APPLICATION_ID='31xxxxxxxx07'
--New
select a.*, substring(a.REJECTION_COMMENTS, b.number, charindex('|', a.REJECTION_COMMENTS + '|', b.number) - b.number) as name
from APPLICATION_COMMENTS_R a
join master..spt_values b on b.type = 'P'
where charindex('|', '|' + a.REJECTION_COMMENTS, b.number) = b.number
and a.APPLICATION_ID='31xxxxxxxx07'
1.建表
students–学生表
建表
create table Students(
sid varchar(10),
sname varchar(10),
sage datetime,
ssex nvarchar(10)
);
--学生表
Student(SId,Sname,Sage,Ssex)
--SId 学生编号,Sname 学生姓名,Sage 出生年月,Ssex 学生性别
teacher–教师表
建表
create table Teacher(
tid varchar(10),
tname varchar(10)
);
--教师表
Teacher(TId,Tname)
--TId 教师编号,Tname 教师姓名
SC–成绩表
建表
create table SC(
sid varchar(10),
cid varchar(10),
score decimal(18,1)
);
--成绩表
SC(SId,CId,score)
--SId 学生编号,CId 课程编号,score 分数
course–课程表
建表
create table Course(
cid varchar(10),
cname varchar(10),
tid varchar(10)
);
--课程表
Course(CId,Cname,TId)
--CId 课程编号,Cname 课程名称,TId 教师编号
2.查询语句
题目
1、查询“01”课程比“02”课程成绩高的所有学生的学号；
方式一：
select sc01.sid
from (select * from sc where cid="01") as sc01 left join (select * from sc where cid="02") as sc02 on sc01.sid=sc02.sid
where sc01.score>sc02.score;
方式二：
select
a.sid,
a.a01,
a.a02,
row_number() over(partition by a.sid order by a.sid ) aindex
from (
select
student.sid,
sum(case when sc.cid='01' then score end) as 'a01',
sum(case when sc.cid='02' then score end) as 'a02'
from student,sc,course,teacher
where student.sid=sc.sid and sc.cid=course.cid and course.tid=teacher.tid
group by student.sid) a
where a.a01 > a.a02
2、查询平均成绩大于60分的同学的学号和平均成绩；
SELECT sid,round(avg(score),2) AS 平均成绩
FROM sc
GROUP BY sid
HAVING avg(score)>60;
3、查询所有同学的学号、姓名、选课数、总成绩
SELECT students.sid,students.sname,count(*) as 选课数,sum(SC.score) as 总成绩
FROM students LEFT JOIN SC ON students.sid=SC.sid
GROUP BY students.sid;
4、查询姓“李”的老师的个数；
select count(*) as 姓李老师的个数
from teacher
where tname like "李%";
5、查询没学过“张三”老师课的同学的学号、姓名；
方式一：
select sid,sname
from students
where sid not in (
select sid
from sc
where cid =(
select cid
from course
where tid=(
select tid
from teacher
where tname="张三"
)
)
);
方式二：
select *
from(
select
cs.cid,
cs.cname,
Student.sid,
SC.score,
Student.sname,
Student.sage,
Student.ssex,
Teacher.tid,
Teacher.tname
from Course cs,SC,Student,Teacher
where Teacher.tid=cs.tid and cs.cid=Sc.cid and sc.sid=Student.sid
) a
where a.tname<>'张三'
6、查询学过编号“01”并且也学过编号“02”课程的同学的学号、姓名；
select students.sid,students.sname
from students left join sc on students.sid=sc.sid
where cid in("01","02")
group by students.sid
having count(*)=2;
7、查询学过“张三”老师所教的课的同学的学号、姓名；
select students.sid,students.sname from students left join (
select * from sc where cid=(
select cid from course where tid=(
select tid from teacher where tname="张三"
)
)
) as zhang on students.sid=zhang.sid;
8、查询课程编号“01”的成绩比课程编号“02”课程低的所有同学的学号、姓名；
select *
from students left join (
select sid
,sum(if(cid="01",score,0)) as "01"
,sum(if(cid="02",score,0)) as "02"
from sc
group by sid) as guan on students.sid=guan.sid
where guan.01<guan.02;
9、查询所有课程成绩小于60分的同学的学号、姓名；
select students.sid,students.sname
from students right join (
select sid
from sc
group by sid
having count(*)=sum(if(score<60,1,0))
) as guan on students.sid=guan.sid;
10、查询没有学全所有课的同学的学号、姓名；
select students.sid,students.sname
from students right join (
select sid
from sc
group by sid
having count(*)!=3
) as guan on students.sid=guan.sid;
11、查询至少有一门课与学号为“01”的同学所学相同的同学的学号和姓名；
select distinct students.sid,students.sname
from students left join sc on students.sid=sc.sid
where cid in(select cid from sc where sid="01");
12、查询和"01"号的同学学习的课程完全相同的其他同学的学号和姓名
方式一
select sid,sname
from Student
where sid in(
select sid
from (
select distinct sid,
cid = ( stuff( (select ',' + cid from SC where sid = a.sid for xml path('')), 1, 1, '' ) )
from SC as a
) b
where cid =(
select cid from(
select * from (
select distinct sid, cid = ( stuff((select ',' + cid from SC where sid = a.sid for xml path('')), 1, 1, '' ) )
from SC as a
) b
) c
where sid=01)
)
方式二
select t1.sid,sname
from(
select sc.sid,count(distinct sc.cid) as count_
from(
select cid
from sc
where sid='01'
)t1 --#选出01的同学所学的课程
left join sc
on t1.cid=sc.cid
group by sc.sid
having count(distinct sc.cid)= (select count(distinct cid) from sc where sid = '01')
) t1
left join student
on t1.sid=student.sid
where t1.sid!='01'
13、把“SC”表中“张三”老师教的课的成绩都更改为此课程的平均成绩；
update dd
set
dd.score =(
select Convert(decimal(18,2),AVG(score))
from Course c,Teacher t,SC s
where t.tid=c.tid and s.cid=c.cid
group by t.tname
having tname='张三'
)
from(
select *
from(
select c.cid,cname,t.tid,tname,sid,score
from Course c,Teacher t,SC s
where t.tid=c.tid and s.cid=c.cid
) cc
where cc.tname='张三'
) dd
14、查询没学过"张三"老师讲授的任一门课程的学生姓名
select distinct sname
from
(
select
c.cid,cname,t.tid,tname,s.sid,score,sname,sage,ssex
from Course c,Teacher t,SC s,Student st
where t.tid=c.tid and s.cid=c.cid and st.sid=s.sid
) a
where a.tname <> '张三'
15、查询两门及其以上不及格课程的同学的学号，姓名及其平均成绩
select
sid,
sname,
Convert(decimal(18,2),AVG(score)) as 'scoreAvg'
from
(
select
c.cid,cname,t.tid,tname,s.sid,score,sname,sage,ssex
from Course c,Teacher t,SC s,Student st
where t.tid=c.tid and s.cid=c.cid and st.sid=s.sid
) a
group by sid,sname
having sum(case when score<60 then 1 else 0 end) >=2
16、检索"01"课程分数小于60，按分数降序排列的学生信息
select
sid,sname,sage,ssex,cid,cname,score
from
(
select
c.cid,cname,t.tid,tname,s.sid,score,sname,sage,ssex
from Course c,Teacher t,SC s,Student st
where t.tid=c.tid and s.cid=c.cid and st.sid=s.sid
) a
where cid='01' and score<60
order by score desc
17、按平均成绩从高到低显示所有学生的平均成绩
select
sid,sname,Convert(decimal(18,2),AVG(score)) as 'scoreAvg'
from
(
select
c.cid,cname,t.tid,tname,s.sid,score,sname,sage,ssex
from Course c,Teacher t,SC s,Student st
where t.tid=c.tid and s.cid=c.cid and st.sid=s.sid
) a
group by sid,sname
order by AVG(score) desc
18、查询各科成绩最高分、最低分和平均分：以如下形式显示：课程ID，课程name，最高分，最低分，平均分，及格率
select
cid,cname,
MAX(score) max,
MIN(score) min,
case when
SUM(case when score>=0 then 1 else 0 end)=0 then '0.00%'
else
convert(varchar,CONVERT(decimal(18, 2),100*(SUM(case when score>=60 then 1 else 0 end))) * 1.0 / SUM(case when score>=0 then 1 else 0 end))+'%'
end '及格率'
from
(
select
c.cid,cname,t.tid,tname,s.sid,score,sname,sage,ssex
from Course c,Teacher t,SC s,Student st
where t.tid=c.tid and s.cid=c.cid and st.sid=s.sid
) a
group by cid,cname
19、按各科平均成绩从低到高和及格率的百分数从高到低顺序
select
cid,cname,
AVG(score) avg_,
case when
SUM(case when score>=0 then 1 else 0 end)=0 then '0.00%'
else
convert(varchar,CONVERT(decimal(18, 2),100*(SUM(case when score>=60 then 1 else 0 end))) * 1.0 / SUM(case when score>=0 then 1 else 0 end))+'%'
end passingRate
from
(
select
c.cid,cname,t.tid,tname,s.sid,score,sname,sage,ssex
from Course c,Teacher t,SC s,Student st
where t.tid=c.tid and s.cid=c.cid and st.sid=s.sid
) a
group by cid,cname
order by avg_ asc,passingRate desc
20、查询学生的总成绩并进行排名
select sid,sname,SUM(score) scoreSum
from
(
select
c.cid,cname,t.tid,tname,s.sid,score,sname,sage,ssex
from Course c,Teacher t,SC s,Student st
where t.tid=c.tid and s.cid=c.cid and st.sid=s.sid
) a
group by sid,sname
order by scoreSum desc
21、查询不同老师所教不同课程平均分从高到低显示
select tid,tname,cname,AVG(score) scoreAvg
from
(
select
c.cid,cname,t.tid,tname,s.sid,score,sname,sage,ssex
from Course c,Teacher t,SC s,Student st
where t.tid=c.tid and s.cid=c.cid and st.sid=s.sid
) a
group by tid,tname,cname
order by scoreAvg desc
22、查询所有课程的成绩第2名到第3名的学生信息及该课程成绩
select sid,sname,sage,ssex,cid,cname,score,aindex
from
(
select
c.cid,cname,t.tid,tname,s.sid,score,sname,sage,ssex,
row_number() over(partition by c.cid order by s.sid ) aindex
from Course c,Teacher t,SC s,Student st
where t.tid=c.tid and s.cid=c.cid and st.sid=s.sid
) a
where aindex between 2 and 3
23、统计各科成绩各分数段人数：课程编号,课程名称,[100-85],[85-70],[70-60],[0-60]及所占百分比
select
cid,cname,
SUM(case when score between 0 and 60 then 1 else 0 end) [0-60],
Round(convert(float,SUM(case when score between 0 and 60 then 1 else 0 end))/convert(float,COUNT(score)),2) 占比,
SUM(case when score between 60 and 70 then 1 else 0 end ) [60-70],
Round(convert(float,SUM(case when score between 60 and 70 then 1 else 0 end ))/convert(float,COUNT(score)),2) 占比,
SUM(case when score between 70 and 85 then 1 else 0 end ) [70-85],
Round(convert(float,SUM(case when score between 70 and 85 then 1 else 0 end ))/convert(float,COUNT(score)),2) 占比,
SUM(case when score between 85 and 100 then 1 else 0 end )[85-100],
Round(convert(float,SUM(case when score between 85 and 100 then 1 else 0 end ))/convert(float,COUNT(score)),2) 占比
from
(
select
c.cid,cname,t.tid,tname,s.sid,score,sname,sage,ssex,
row_number() over(partition by c.cid order by s.sid ) aindex
from Course c,Teacher t,SC s,Student st
where t.tid=c.tid and s.cid=c.cid and st.sid=s.sid
) a
group by cid,cname
24、查询学生平均成绩及其名次
select sid,sname,AVG(score) avgScore,
row_number() over(order by AVG(score) desc) number
from
(
select
c.cid,cname,t.tid,tname,s.sid,score,sname,sage,ssex
from Course c,Teacher t,SC s,Student st
where t.tid=c.tid and s.cid=c.cid and st.sid=s.sid
) a
group by sid,sname
25、查询各科成绩前三名的记录
select *
from
(
select
c.cid,cname,t.tid,tname,s.sid,score,sname,sage,ssex,
row_number() over(partition by c.cid order by score desc) aindex
from Course c,Teacher t,SC s,Student st
where t.tid=c.tid and s.cid=c.cid and st.sid=s.sid
) a
where aindex between 1 and 3
26、查询每门课程被选修的学生数
select cid,cname,COUNT(*) 人数
from
(
select
c.cid,cname,t.tid,tname,s.sid,score,sname,sage,ssex
from Course c,Teacher t,SC s,Student st
where t.tid=c.tid and s.cid=c.cid and st.sid=s.sid
) a
group by cid,cname
27、查询出只选修了两门课程的全部学生的学号和姓名
select sid,sname
from
(
select sid,sname,cid,cname,row_number() over(partition by sid order by score desc) aindex
from
(
select
c.cid,cname,t.tid,tname,s.sid,score,sname,sage,ssex
from Course c,Teacher t,SC s,Student st
where t.tid=c.tid and s.cid=c.cid and st.sid=s.sid
) a
)b
group by sid,sname
having COUNT(sid)=2
28、查询男生、女生人数
select
sum(case when ssex='男' then 1 else 0 end) 男,
sum(case when ssex='女' then 1 else 0 end) 女
from Student
29、查询名字中含有"风"字的学生信息
select *
from Student
where sname like '%风%'
30、查询同名同性学生名单，并统计同名人数
select
sname,ssex,
row_number() over(partition by sname,ssex order by sid desc) aindex,
case when COUNT(sname)=1 then '无' else sname end 同名人
from Student
group by sname,ssex,sid
31、查询1990年出生的学生名单(注：Student表中Sage列的类型是datetime)
select *
from Student
where YEAR(sage)=1990
32、查询每门课程的平均成绩，结果按平均成绩升序排列，平均成绩相同时，按课程号降序排列
select cid,cname,AVG(score) 平均成绩
from
(
select
c.cid,cname,t.tid,tname,s.sid,score,sname,sage,ssex,
row_number() over(partition by c.cid order by score desc) aindex
from Course c,Teacher t,SC s,Student st
where t.tid=c.tid and s.cid=c.cid and st.sid=s.sid
) a
group by cid,cname
order by AVG(score),cid desc
37、查询不及格的课程，并按课程号从大到小排列
select
cid,cname,
SUM(case when score between 0 and 60 then 1 else 0 end) 不及格人数,
case when AVG(score)<60 then '是' else '否' end 不及格课程
from
(
select
c.cid,cname,t.tid,tname,s.sid,score,sname,sage,ssex,
row_number() over(partition by c.cid order by score desc) aindex
from Course c,Teacher t,SC s,Student st
where t.tid=c.tid and s.cid=c.cid and st.sid=s.sid
) a
group by cid,cname
having AVG(score)<60
order by cid desc
38、查询课程编号为"01"且课程成绩在60分以上的学生的学号和姓名；
select sid,sname
from
(
select
c.cid,cname,t.tid,tname,s.sid,score,sname,sage,ssex
from Course c,Teacher t,SC s,Student st
where t.tid=c.tid and s.cid=c.cid and st.sid=s.sid
) a
where cid=01 and score>60
40、查询选修“张三”老师所授课程的学生中，成绩最高的学生姓名及其成绩
select *
from
(
select
c.cid,cname,t.tid,tname,s.sid,score,sname,sage,ssex,
row_number() over(partition by c.cid order by score desc) aindex
from Course c,Teacher t,SC s,Student st
where t.tid=c.tid and s.cid=c.cid and st.sid=s.sid
) a
where tname='张三' and aindex=1
42、查询每门功课成绩最好的前两名
select *
from
(
select
c.cid,cname,t.tid,tname,s.sid,score,sname,sage,ssex,
row_number() over(partition by c.cid order by score desc) aindex
from Course c,Teacher t,SC s,Student st
where t.tid=c.tid and s.cid=c.cid and st.sid=s.sid
) a
where aindex between 1 and 2
43、统计每门课程的学生选修人数（超过5人的课程才统计）。要求输出课程号和选修人数，查询结果按人数降序排列，若人数相同，按课程号升序排列
select cid,cname,COUNT(sid)
from
(
select
c.cid,cname,t.tid,tname,s.sid,score,sname,sage,ssex,
row_number() over(partition by c.cid order by score desc) aindex
from Course c,Teacher t,SC s,Student st
where t.tid=c.tid and s.cid=c.cid and st.sid=s.sid
) a
group by cid,cname
having COUNT(sid)>=5
order by COUNT(sid) desc,cid
44、检索至少选修两门课程的学生学号
select sid,sname,COUNT(sid) 选课数
from
(
select
s.sid,score,sname,sage,ssex,c.cid,cname,t.tid,tname,
row_number() over(partition by s.sid order by score desc) aindex
from Course c,Teacher t,SC s,Student st
where t.tid=c.tid and s.cid=c.cid and st.sid=s.sid
) a
group by sid,sname
having COUNT(sid)>=2
45、查询选修了全部课程的学生信息
select sid,sname,sage,ssex,COUNT(sid) 选课数
from
(
select
s.sid,score,sname,sage,ssex,c.cid,cname,t.tid,tname,
row_number() over(partition by s.sid order by score desc) aindex
from Course c,Teacher t,SC s,Student st
where t.tid=c.tid and s.cid=c.cid and st.sid=s.sid
) a
group by sid,sname,sage,ssex
having COUNT(sid)=3
46、查询各学生的年龄
select sage
from Student
47、查询本周过生日的学生
select *
from student
where weekofyear(sage)=weekofyear(curdate()) --mysql
48、查询下周过生日的学生
select *
from student
where weekofyear(sage) = weekofyear(date_add(curdate(),interval 1 week)) --mysql
49、查询本月过生日的学生
select *
from student
--where month(sage) = month(curdate()) --mysql
where MONTH(getdate())-MONTH(sage)=0 --sqlserver
50、查询下月过生日的学生
select *
from student
--where month(date_sub(sage,interval 1 month)) = month(curdate()) --mysql
where MONTH(getdate())-MONTH(sage)=-1 --sqlserver