五大数据库常用SQL比较(三)
2012-06-05 16:10
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四十九、生成累计和
db2/oracle
select ename,sal,sum(sal) over (order by sal,empno) as running_total from emp order by 2
mysql/postgresql/sqlserver
select e.ename,e.sal,(select sum(d.sal) from emp d where d.empno< =e.empno) as running_total from emp e order by 3
五十、生成累乘积
db2/oracle
select empno,ename,sal,exp(sum(ln(sal)) over (order by sal,empno)) as running_prod from emp where deptno=10
select empno,ename,sal,tmp as running_prod from (select empno,ename,-sal as sal from emp where deptno=10) model dimension by(row_number() over(order by sal desc) rn) measures(sal,0 tmp,empno,ename) rules(tmp[any]=case when sal[cv()-1] is null then sal[cv()]
else tmp[cv()-1]*sal[cv()] end )
mysql/postgresql/sqlserver
select e.empno,e.ename,e.sal,(select exp(sum(ln(d.sal))) from emp d where d.empno<=e.empno and e.deptno=d.deptno) as running_prod from emp e where e.deptno=10
五十一、生成累计差
db2/oracle
select ename,sal,sum(case when rn=1 then sal else -sal end) over(order by sal,empno) as
running_diff from (select empno,ename,sal,row_number() over(order by sal,empno) as rn from
emp where deptno=10) x
mysql/postgresql/sqlserver
select a.empno,a.ename,a.sal,(select case when a.empno=min(b.empno) then sum(b.sal) else
sum(-b.sal) end from emp b where b.empno<=a.empno and b.deptno=a.deptno ) as rnk from emp a
where a.deptno=10
五十二、计算模式
db2/sqlserver
select sal from (select sal,dense_rank() over(order by cnt desc) as rnk from (select
sal,count(*) as cnt from emp where deptno=20 group by sal) x) y where rnk=1
oracle
select max(sal) keep(dense_rank first order by cnt desc) sal from (select sal,count(*) cnt
from emp where deptno=20 group by sal)
mysql/postgresql
select sal from emp where deptno=20 group by sal having count(*) >=all(select count(*) from
emp where deptno=20 group by sal)
五十三、计算中间值
db2
select avg(sal) from (select sal,count(*) over() total cast(count(*) over() as desimal)/2
mid,ceil(cast(count(*) over as decimal)/2) next,row_number() over (order by sal) rn from emp
where deptno=20) x where (mod(total,2)=0 and rn in(mid,mid+1)) or (mod(total,2)=1 and
rn=next)
mysql/postgresql
select avg(sal) from (select e.sal from emp e,emp d where e.deptno=d.deptno and e.deptno=20
group by e.sal having sum(case when e.sal=d.sal then 1 else 0 end)>=abs(sum(sign(e.sal-
d.sal))))
oracle
select median(sal) from emp where deptno=20
select percentile_cont(0.5) within group(order by sal) from emp where deptno=20
sqlserver
select avg(sal) from (select sal,count(*) over() total,cast(count(*) over() as decimel)/2
mid,ceiling(cast(count(*) over() as decimal)/2) next,row_number() over(order by sal) rn from
emp where deptno=20) x where (total%2=0 and rn in(mid,mid+1)) or(total%2=1 and rn=next)
五十四、求总和的百分比
mysql/postgresql
select (sum(case when deptno=10 then sal end)/sum(sal))*100 as pct from emp
db2/oracle/sqlserver
select distinct (d10/total)*100 as pct from (select deptno,sum(sal) over() total,sum(sal)
over(partition by deptno) d10 from emp) x where deptno=10
五十五、对可空列作聚集
select avg(coalesce(comm,0)) as avg_comm from emp where deptno=30
五十六、计算不包含最大值和最小值的均值
mysql/postgresql
select avg(sal) from emp where sal not in((select min(sal) from emp),(select max(sal) from
emp))
db2/oracle/sqlserver
select avg(sal) from (select sal,min(sal) over() min_sal,max(sal) over() max_sal from emp) x
where sal not in(min_sal,max_sal)
五十七、把字母数字串转换为数值
db2
select cast(replace(translate(’paul123f321′,repeat
(’#',26),’abcdefghijklmnopqrstuvwxyz’),’#',”) as integer) as num from t1
oracle/postgresql
select cast(replace(translate(’paul123f321′,’abcdefghijklmnopqrstuvwxyz’,rpad
(’#',26′#’)),’#',”) as integer ) as num from t1
五十八、更改累计和中的值
db2/oracle
select case when trx=’PY’ then ‘PAYMENT’ else ‘PURCHASE’ end trx_type,amt,sum(case when
trx=’PY’ then -amt else amt end) over (order by id,amt) as balance from V
mysql/postgresql/sqlserver
select case when v1.trx=’PY’ then ‘PAYMENT’ else ‘PURCHASE’ end as trx_type,v1.amt,(select sum(case when v2.trx=’PY’ then -v2.amt else v2.amt end) from V v2 where v2.id< =v1.id) as balance from V v1
五十九、增加或减少日，月，年
db2
select hiredate -5 day as hd_minus_5D,hiredate +5 day as hd_plus_5D,hiredate -5 month as
hd_minus_5M,hiredate +5 month as hd_plus_5M,hiredate -5 year as hd_minus_5Y,hiredate +5 year
as hd_plus_5Y from emp where deptno=10
oracle
select hiredate-5 as hd_minus_5D,hiredate+5 as hd_plus_5D,add_months(hiredate,-5) as
hd_minus_5M,add_months(hiredate,5) as hd_plus_5M,add_months(hiredate,-5*12) as
hd_minus_5Y,add_months(hiredate,5*120 as hd_plus_5Y from emp where deptno=10
postgresql
select hiredate-interval '5 day' as hd_minus_5D,hiredate+interval '5 day' as
hd_plus_5D,hiredate-interval '5 month' as hd_minus_5M,hiredate+interval '5 month' as
hd_plus_5M,hiredate-interval '5 year' as hd_minus_5Y,hiredate+interval '5 year' as
hd_plus_5Y from emp where deptno=10
mysql
select hiredate-interval 5 day as hd_minus_5D,hiredate+interval 5 day as
hd_plus_5D,hiredate-interval 5 month as hd_minus_5M,hiredate+interval 5 month as
hd_plus_5M,hiredate-interval 5 year as hd_minus_5Y,hiredate+interval 5 year as hd_plus_5Y
from emp where deptno=10
select date_add(hiredate,interval -5 day) as hd_minus_5D,date_add(hiredate,interval 5 day)
as hd_plus_5D,date_add(hiredate,interval -5 month) as hd_minus_5M,date_add(hiredate,interval
5 month) as hd_plus_5M,date_add(hiredate,interval -5 year) as hd_minus_5Y,date_add
(hiredate,interval 5 year) as hd_plus_5Y from emp where deptno=10
sqlserver
select dateadd(day,-5,hiredate) as hd_minus_5D,dateadd(day,5,hiredate0 as
hd_plus_5D,dateadd(month,-5,hiredate) as hd_minus_5M,dateadd(month,5,hiredate) as
hd_plus_5M,dateadd(year,-5,hiredate) as hd_minus_5Y,dateadd(year,5,hiredate) as hd_plus_5Y
from emp where deptno=10
六十、计算2个日期之间的天数
db2
select days(ward_hd) - days(allen_hd) from (select hiredate as ward_hd from emp where
ename='WARD') x,(select hiredate as allen_hd from emp where ename='ALLEN') y
oracle/postgresql
select ward_hd - allen_hd from (select hiredate as ward_hd from emp where ename='WARD') x,
(select hiredate as allen_hd from emp where ename='ALLEN') y
mysql/sqlserver
select datediff(day,allen_hd,ward_hd) from select hiredate as ward_hd from emp where ename =
'WARD') x,(select hiredate as allen_hd from emp where ename='ALLEN') y
六十一、计算2个日期之间的工作日天数
db2
select sum(case when dayname(jones_hd+t500.id day -1 day) in ('Saturday','Sunday') then 0
else 1 end) as days from (select max(case when ename='BLAKE' then hiredate end) as
blake_hd,max(case when ename='JONES' then hiredate end) as jones_hd from emp where ename in
('BLAKE','JONES') ) x,t500 where t500.id <=blake_hd-jones_hd+1
mysql
select sum(case when date_format(date_add(jones_hd,interval t500.id-1 DAY),'%a') in
('Sat','Sun') then 0 else 1 end) as days from (select max(case when ename='BLAKE' then
hiredate end) as blake_hd,max(case when ename='JONES' then hiredate end) as jones_hd from
emp where ename in ('BLAKE','JONES') ) x,t500 where t500.id<=datediff(blake_hd,jones_hd)+1
oracle
select sum(case when to_char(jones_hd+t500.id-1,'DY') in ('SAT','SUN') then 0 else 1 end) as
days from ( select max(case when ename='BLAKE' then hiredate end ) as blake_hd,max(case when
ename='JONES' then hiredate end) as jones_hd from emp where ename in ('BLAKE','JONES') )
x,t500 where t500.id<=blake_hd-jones_hd+1
postgresql
select sum(case when trim(to_char(jones_hd+t500.id-1,'DAY')) in ('SATURDAY','SUNDAY') then 0
else 1 end) as days from (select max(case when ename='BLAKE' then hiredate end) as
blake_hd,max(case when ename='JONES' then hiredate end) as jones_hd from emp where ename in
('BLAKE','JONES') ) x,t500 where t500.id<=blake_hd-jones_hd+1
sqlserver
select sum(case when datename(dw,jones_hd+t500.id-1) in ('SATURDAY','SUNDAY') then 0 else 1
end) as days from ( select max(case when ename='BLAKE' then hiredate end) as blake_hd,max
(case when ename='JONES' then hiredate end) as jones_hd from emp where ename in
('BLAKE','JONES') ) x,t500 where t500.id<=datediff(day,jones_hd-blake_hd)+1
六十二、计算2个日期之间的月和年
db2/mysql
select mnth,mnth/12 from (select (year(max_hd)-year(min_hd))*12+(month(max_hd)-month
(min_hd)) as mnth from (select min(hiredate) as min_hd,max(hiredate) as max_hd from emp ) x
) y
oracle
select months_between(max_hd,min_hd),months_between(max_hd,min_hd)/12 from (select min
(hiredate) min_hd,max(hiredate) max_hd from emp ) x
postgresql
select mnth,mnth/12 from ( select extract(year from max_hd) extract(year from min_hd))*12 +
(extract(month from max_hd) extract(month from min_hd)) as mnth from (select min(hiredate)
as min_hd,max(hiredate) as max_hd from emp ) x ) y
sqlserver
select datediff(month,min_hd,max_hd),datediff(month,min_hd,max_hd)/12 from (select min
(hiredate) min_hd,max(hiredate) max_hd from emp ) x
六十三、计算2个日期之间的秒、分、小时
db2
select dy*24 hr,dy*24*60 min,day*24*60*60 sec from (select (days(max(case when ename='WARD'
then hiredate end))-days(max(case when ename='ALLEN' then hiredate end)) ) as dy from emp )
x
mysql/sqlserver
select datediff(day,allen_hd,ward_hd)*24 hr,datediff(day,allen_hd,ward_hd)*24*60
min,datediff(day,allen_hd,ward_hd)*24*60*60 sec from (select max(case when ename='WARD' then
hiredate end) as ward_hd,max(case when ename='ALLEN' then hiredate end) as allen_hd from emp
) x
oracle/postgresql
select dy*24 as hr,dy*24*60 as min,dy*24*60*60 as sec from (select (max(case when
ename='WARD' then hiredate end)-max(case when ename='ALLEN' then hiredate end)) as dy from
emp ) x
六十四、统计一年中的周日的天数
db2
with x (start_date,end_date) as ( select start_date,start_date+1 year end_date from (select
(current_date dayofyear(current_date) day)+1 day as start_date from t1) tmp union all select
start_date+1 day,end_date from x where start_date+1 day (start_date),count(*) from x group by dayname(start_date)
mysql
select date_format(date_add(cast(concat(year(current_date),'-01-01') as date),interval
t500.id-1 day),'%W') day,count(*) from t500 where t500.id<=datediff(cast(concat(year
(current_date)+1,'-01-01') as date),cast(concat(year(current_date),'-01-01') as date)) group
by date(format(date_add(cast(concat(year(current_date),'-01-01') as date),interval t500.id-1
day),'%W')
oracle
with x as (select level lvl from dual connect by level<=(add_months(trunc(sysdate,'y'),12)-
trunc(sysdate,'y'))) select to_char(trunc(sysdate,'y')+lvl-1,'DAY'),count(*) from x group by
to_char(trunc(sysdate,'y')+lvl-1,'DAY')
select to_char(trunc(sysdate,'y')+rownum-1,'DAY'),count(*) from t500 where rownum<=
(add_months(trunc(sysdate,'y'),12)-trunc(sysdate,'y')) group by to_char(trunc(sysdate,'y')
+rownum-1,'DAY')
postgresql
select to_char(cast(date_trunc('year',current_date) as date+gs.id-1,'DAY'),count(*) from
generate_series(1,366) gs(id) where gs.id<=(cast(date_trunc('year',current_date)+interval
'12 month' as date)-cast(date_trunc('year',current_date) as date)) group by to_char(cast
(date_trunc('year',current_date) as date) + gs.id-1,'DAY')
sqlserver
with x (start_date,end_date) as (select start_date,dateadd(year,1,start_date) end_date from
(select cast(cast(year(getdate()) as varchar) +'-01-01' as datetime) start_date from t1 )
tmp union all select dateadd(day,1,start_date),end_date from x where dateadd
(day,1,start_date) datename(dw,start_date) OPTION (MAXRECURSION 366)
六十五、查看2个记录之间的日期不同
db2
select x.*,days(x.next_hd)-days(x.hiredate) diff from (select e.deptno,e.name,e.hiredate,
(select min(d.hiredate) from emp d where d.hiredate>e.hiredate) next_hd from emp e where
e.deptno=10) x
mysql/sqlserver
select x.*,datediff(day,x.hiredate,x.next_hd) diff from (select
e.deptno,e.ename,e.hiredate,(select min(d.hiredate) from emp d where d.hiredate>e.hiredate)
next_hd from emp e where e.deptno=10 ) x
oracle
select ename,hiredate,next_hd,next_hd-hiredate diff from (select deptno,ename,hiredate,lead
(hiredate) over(order by hiredate) next_hd from emp ) where deptno=10
postgresql
select x.*,x.next_hd-x.hiredate as diff from (select e.deptno,e.ename,e.hiredate,(select
min(d.hiredate) from emp d where d.hiredate>e.hiredate) as next_hd from emp e where
e.deptno=10 ) x
六十六、判断这一年是不是闰年
db2
with x (dy,mth) as ( select dy,month(dy) from (select (current_date-dayofyear(current_date)
days+1 days)+1 months as dy from t1) tmp1 union all select dy+1 days,mth from x where month
(dy+1 day)=mth) select max(day(dy) from x
oracle
select to_char(last_day(add_months(trunc(sysdate,’y'),1)),’DD’) from t1
postgresql
select max(to_char(tmp2.dy+x.id,’DD’)) as dy from ( select dy,to_char(dy,’MM’) as mth from
(select cast(cast(date_trunc(’year’,current_date) as date)+interval ‘1 month’ as date) as dy
from t1) tmp1 ) tmp2,generate_series (0,29) x(id) where to_char(tmp2.dy+x.id,’MM’)=tmp2.mth
mysql
select day(last_day(date_add(date_add(date_add(current_date,interval -dayofyear
(current_date) day),interval 1 day),interval 1 month))) dy from t1
sqlserver
with x (dy,mth) as (select dy,month(dy) from (select dateadd(mm,1,(getdate()-datepart
(dy,getdate()))+1) dy from t1) tmp1 union all select dateadd(dd,1,dy),mth from x where
month(dateadd(dd,1,dy))=mth) select max(day(dy)) from x
六十七、计算这一年中有多少天
db2
select days((curr_year+1 year))-days(curr_year) from (select (current_date-dayofyear
(current_date) day+1 day) curr_year from t1 ) x
oracle
select add_months(trunc(sysdate,’y'),12)-trunc(sysdate,’y') from dual
postgresql
select cast((curr_year+interval ‘1 year’) as date) - curr_year from ( select cast
(date_trunc(’year’,current_date) as date) as curr_year from t1 ) x
mysql
select datediff((curr_year+interval 1 year),curr_year) from ( select adddate(current_date,-
dayofyear(current_date)+1) curr_year from t1 ) x
sqlserver
select datediff(d,curr_year,dateadd(yy,1,curr_year)) from ( select dateadd(d,-datepart
(dy,getdate())+1,getdate()) curr_year from t1 ) x
六十八、分解日期—-小时、分、秒、日、月、年
db2
select hour(current_timestamp) hr,minute(current_timestamp) min,second(current_timestamp)
sec,day(current_timestamp) dy,month(current_timestamp) mth,year(current_timestamp) yr from
t1
oracle
select to_number(to_char(sysdate,’hh24′)) hour,to_number(to_char(sysdate,’mi’))
min,to_number(to_char(sysdate,’ss’)) sec,to_number(to_char(sysdate,’dd’)) day,to_number
(to_char(sysdate,’mm’)) mth,to_number(to_char(sysdate,’yyyy’)) year from dual
postgresql
select to_number(to_char(current_timestamp,’hh24′),’99′) as hr,to_number(to_char
(current_timestamp,’mi’),’99′) as min,to_number(to_char(current_timestamp,’ss’),’99′) as
sec,to_number(to_char(current_timestamp,’dd’),’99′) as day,to_number(to_char
(current_timestamp,’mm’),’99′) as mth,to_number(to_char(current_timestamp,’yyyy’),’9999′) as
yr from t1
mysql
select date_format(current_timestamp,’%k’) hr,date_format(current_timestamp,’%i’)
min,date_format(current_timestamp,’%s’) sec,date_format(current_timestamp,’%d’)
dy,date_format(current_timestamp,’%m’) mon,date_format(current_timestamp,’%Y’) yr from t1
sqlserver
select datepart(hour,getdate()) hr,datepart(minute,getdate()) min,datepart(second,getdate())
sec,datepart(day,getdate()) dy,datepart(month,getdate()) mon,datepart(year,getdate()) yr
from t1
六十九、计算一个月的第一天和最后一天
db2
select (current_date-day(current_date) day+1 day) firstday,(current_date+1 month -day
(current_date) day) lastday from t1
oracle
select trunc(sysdate,’mm’) firstday,last_day(sysdate) lastday from dual
postgresql
select firstday,cast(firstday+interval ‘1 month’-interval ‘1 day’ as date) as lastday from (
select cast(date_trunc(’month’,current_date) as date) as firstday from t1) x
mysql
select date_add(current_date,interval -day(current_date)+1 day) firstday,last_day
(current_date) lastday from t1
sqlserver
select dateadd(day,-day(getdate())+1,getdate()) firstday,dateadd(day,-day(getdate(),dateadd
(month,1,getdate())) lastdate from t1
七十、计算出一年中的一周中某一天的日期
db2
with x (dy,yr) as ( select dy,year(dy) yr from (select (current_date-dayofyear(current_date)
days +1 days) as dy from t1) tmp1 union all select dy+1 days,yr from x where year(dy+1 day)
=yr) select dy from x where dayname(dy)=’Friday’
oracle
with x as (select trunc(sysdate,’y')+level-1 dy from dual connect by level< =add_months(trunc(sysdate,'y'),12)-trunc(sysdate,'y')) select * from x where to_char(dy-1,'d') ='5'
postgresql
select cast(date_trunc('year',current_date) as date)+x.id as dy from generate_series( 0,
(select cast(cast(date_trunc('year',current_date) as date) + interval '1 years' as date)-
cast(date_trunc('year',current_date) as date))-1 ) x(id) where to_char(cast(date_trunc
('year',current_date) as date)+x.id,'dy')='fri'
mysql
select dy from (select adddate(x.dy,interval t500.id-1 day) dy from (select dy,year(dy) yr
from (select adddate(adddate(current_date,interval -dayofyear(current_date) day),interval 1
day ) dy from t1) tmp1 ) x,t500 where year(adddate(x.dy,interval t500.id-1 day))=x.yr) tmp2
where dayname(dy)='Friday'
sqlserver
with x (dy,yr) as ( select dy,year(dy) yr from ( select getdate()-datepart(dy,getdate())+1
dy from t1) tmp1 union all select dateadd(dd,1,dy),yr from x where year(dateadd(dd,1,dy))
=yr) select x.dy from x where datename(dw,x.dy)='Friday' option (maxrecursion 400)
七十一、确定这个月中的第一次出现和最后一次出现的特定的周末
db2
with x (dy,mth,is_monday) as ( select dy,month(dy),case when dayname(dy)='Monday' then 1
else 0 end from (select (current_date-day(current_date) day +1 day) dy from t1) tmp1 union
all select (dy +1 day),mth,case when dayname(dy +1 day)='Monday' then 1 else 0 end from x
where month(dy +1 day)=mth) select min(dy) first_month,max(dy) last_monday from x where
is_monday=1
oracle
select next_day(trunc(sysdate,'mm')-1,'星期一') first_monday,next_day(last_day(trunc
(sysdate,'mm'))-7,'星期一') last_monday from dual
postgresql
select first_monday,case to_char(first_monday+28,'mm') when mth then first_monday+28 else
first_monday+21 end as last_monday from (select case sign(cast(to_char(dy,'d') as integer)
-2) when 0 then dy when -1 then dy+abs(cast(to_char(dy,'d') as integer)-2) when 1 then (7-
(cast(to_char(dy,'d') as integer)-2))+dy end as first_monday,mth from (select cast
(date_trunc('month',current_date) as date) as dy,to_char(current_date,'mm') as mth from t1 )x ) y
mysql
select first_monday,case month(adddate(first_monday,28)) when mth then adddate
(first_monday,28) else adddate(first_monday,21) end last_monday from ( select case sign
(dayofweek(dy)-2) when 0 then dy when -1 then adddate(dy,abs(dayofweek(dy)-2)) when 1 then adddate(dy,(7-(dayofweek(dy)-2))) end first_monday,mth from (select adddate(adddate
(current_date,-day(current_date)),1) dy,month(current_date0 mth from t1) x ) y
sqlserver
with x (dy,mth,is_monday) as ( select dy,mth,case when datepart(dw,dy)=2 then 1 else 0 end
from (select dateadd(day,1,dateadd(day,-day(getdate()),getdate())) dy,month(getdate()) mth
from t1 ) tmp1 union all select dateadd(day,1,dy),mth,case when datepart(dw,dateadd
(day,1,dy))=2 then 1 else 0 end from x where month(dateadd(day,1,dy))=mth ) select min(dy)
first_monday,max(dy) last_monday from x where is_monday=1
七十二、创建一个日历
db2
with x (dy,dm,mth,dw,wk) as ( select (current_date -day(current_date) day +1 day) dy,day
((current_date -day(current_date) day +1 day)) dm,month(current_date) mth,dayofweek
(current_date -day(current_date) day +1 day) dw,week(iso(current_date -day(current_date) day+1 day) wk from t1 union all select dy+1 day,day(dy+1 day),mth,dayofweek(dy+1 day),week_iso(dy+1 day) from x where month(dy+1 day)=mth ) select max(case dw when 2 then
dm end) as Mo,max(case dw when 3 then dm end) as Tu,max(case dw when 4 then dm end) as We,max(case dw when 5 then dm end) as Th,max(case dw when 6 then dm end) as Fr,max(case dw when 7 then dm end) as Sa,max(case dw when 1 then dm end) as Su from x group by
wk order by wk
oracle
with x as ( select * from (select to_char(trunc(sysdate,'mm')+level-1,'iw') wk,to_char
(trunc(sysdate,'mm')+level-1,'dd') dm,to_number(to_char(trunc(sysdate,'mm')+level-1,'d'))
dw,to_char(trunc(sysdate,'mm')+level-1,'mm') curr_mth,to_char(sysdate,'mm') mth from dual
connect by level<=31) where curr_mth<=31) select max(case dw when 2 then dm end) as Mo,max(case dw when 3 then dm end) as Tu,max(case dw when 4 then dm end) as We,max(case dw when 5 then dm end) as Th,max(case dw when 6 then dm end) as Fr,max(case dw when 7
then dm end) as Sa,max(case dw when 1 then dm end) as Su from x group by wk order by wk
postgresql
select max(case dw when 2 then dm end) as Mo,max(case dw when 3 then dm end) as Tu,max(case dw when 4 then dm end) as We,max(case dw when 5 then dm end) as Th,max(case dw when 6 then dm end) as Fr,max(case dw when 7 then dm end) as Sa,max(case dw when 1 then
dm end) as Su from (select * from ( select cast(date_trunc('month',current_date) as date) +x.id,to_char(cast(date_trunc('month',current_date0 as date)+x.id,'iw') as wk,to_char(cast(date_trunc('month',current_date) as date) +x.id,'dd') as dm,cast(to-char(cast(date_trunc('month',current_date)
as date) +x.id,'d') as integer) as dw,to_char(cast(date_trunc('month',current_date) as date) +x.id,'mm') as curr_mth,to_char(current_date,'mm') as mth
from generate_series (0,31) x(id) ) x where mth=curr_mth ) y group by wk order by wk
mysql
select max(case dw when 2 then dm end) as Mo,max(case dw when 3 then dm end) as Tu,max(case dw when 4 then dm end) as We,max(case dw when 5 then dm end) as Th,max(case dw when 6 then dm end) as Fr,max(case dw when 7 then dm end) as Sa,max(case dw when 1 then
dm end) as Su from (select date_format(dy,'%u') wk,date_format(dy,'%d') dm,date_format(dy,'%w')+1 dw from (select adddate(x.dy,t500.id-1) dy,x.mth from (select adddate(current_date,-dayofmonth(current_date)+1) dy,date_format(adddate(current_date,-dayomonth(current_date)+1),'%m')
mth from t1) x,t500 where t500.id<=31 and date_format(adddate(x.dy,t500.id-1),'%m')=x.mth) y ) z group by wk order by wk
sqlserver
with x (dy,dm,mth,dw,wk) as ( select dy,day(dy) dm,datepart(m,dy) mth,datepart(dw,dy)
dw,case when datepart(dw,dy)+1 then datepart(ww,dy)-1 else datepart(ww,dy) end wk from
(select dateadd(day,-day(getdate())+1,getdate()) dy from t1 ) x union all select dateadd
(d,1,dy),day(dateadd(d,1,dy)),mth,datepart(dw,dateadd(d,1,dy)),case when datepart
(dw,dateadd(d,1,dy))=1 then datepart(wk,dateadd(d,1,dy))-1 else datepart(wk,dateadd(d,1,dy)) end from x where datepart(m,dateadd(d,1,dy))=mth) select max(case dw when 2 then dm end) as Mo,max(case dw when 3 then dm end) as Tu,max(case dw when 4 then dm end)
as We,max(case dw when 5 then dm end) as Th,max(case dw when 6 then dm end) as Fr,max(case dw when 7 then dm end) as Sa,max(case dw when 1 then dm end) as Su from x group by wk order by wk
db2/oracle
select ename,sal,sum(sal) over (order by sal,empno) as running_total from emp order by 2
mysql/postgresql/sqlserver
select e.ename,e.sal,(select sum(d.sal) from emp d where d.empno< =e.empno) as running_total from emp e order by 3
五十、生成累乘积
db2/oracle
select empno,ename,sal,exp(sum(ln(sal)) over (order by sal,empno)) as running_prod from emp where deptno=10
select empno,ename,sal,tmp as running_prod from (select empno,ename,-sal as sal from emp where deptno=10) model dimension by(row_number() over(order by sal desc) rn) measures(sal,0 tmp,empno,ename) rules(tmp[any]=case when sal[cv()-1] is null then sal[cv()]
else tmp[cv()-1]*sal[cv()] end )
mysql/postgresql/sqlserver
select e.empno,e.ename,e.sal,(select exp(sum(ln(d.sal))) from emp d where d.empno<=e.empno and e.deptno=d.deptno) as running_prod from emp e where e.deptno=10
五十一、生成累计差
db2/oracle
select ename,sal,sum(case when rn=1 then sal else -sal end) over(order by sal,empno) as
running_diff from (select empno,ename,sal,row_number() over(order by sal,empno) as rn from
emp where deptno=10) x
mysql/postgresql/sqlserver
select a.empno,a.ename,a.sal,(select case when a.empno=min(b.empno) then sum(b.sal) else
sum(-b.sal) end from emp b where b.empno<=a.empno and b.deptno=a.deptno ) as rnk from emp a
where a.deptno=10
五十二、计算模式
db2/sqlserver
select sal from (select sal,dense_rank() over(order by cnt desc) as rnk from (select
sal,count(*) as cnt from emp where deptno=20 group by sal) x) y where rnk=1
oracle
select max(sal) keep(dense_rank first order by cnt desc) sal from (select sal,count(*) cnt
from emp where deptno=20 group by sal)
mysql/postgresql
select sal from emp where deptno=20 group by sal having count(*) >=all(select count(*) from
emp where deptno=20 group by sal)
五十三、计算中间值
db2
select avg(sal) from (select sal,count(*) over() total cast(count(*) over() as desimal)/2
mid,ceil(cast(count(*) over as decimal)/2) next,row_number() over (order by sal) rn from emp
where deptno=20) x where (mod(total,2)=0 and rn in(mid,mid+1)) or (mod(total,2)=1 and
rn=next)
mysql/postgresql
select avg(sal) from (select e.sal from emp e,emp d where e.deptno=d.deptno and e.deptno=20
group by e.sal having sum(case when e.sal=d.sal then 1 else 0 end)>=abs(sum(sign(e.sal-
d.sal))))
oracle
select median(sal) from emp where deptno=20
select percentile_cont(0.5) within group(order by sal) from emp where deptno=20
sqlserver
select avg(sal) from (select sal,count(*) over() total,cast(count(*) over() as decimel)/2
mid,ceiling(cast(count(*) over() as decimal)/2) next,row_number() over(order by sal) rn from
emp where deptno=20) x where (total%2=0 and rn in(mid,mid+1)) or(total%2=1 and rn=next)
五十四、求总和的百分比
mysql/postgresql
select (sum(case when deptno=10 then sal end)/sum(sal))*100 as pct from emp
db2/oracle/sqlserver
select distinct (d10/total)*100 as pct from (select deptno,sum(sal) over() total,sum(sal)
over(partition by deptno) d10 from emp) x where deptno=10
五十五、对可空列作聚集
select avg(coalesce(comm,0)) as avg_comm from emp where deptno=30
五十六、计算不包含最大值和最小值的均值
mysql/postgresql
select avg(sal) from emp where sal not in((select min(sal) from emp),(select max(sal) from
emp))
db2/oracle/sqlserver
select avg(sal) from (select sal,min(sal) over() min_sal,max(sal) over() max_sal from emp) x
where sal not in(min_sal,max_sal)
五十七、把字母数字串转换为数值
db2
select cast(replace(translate(’paul123f321′,repeat
(’#',26),’abcdefghijklmnopqrstuvwxyz’),’#',”) as integer) as num from t1
oracle/postgresql
select cast(replace(translate(’paul123f321′,’abcdefghijklmnopqrstuvwxyz’,rpad
(’#',26′#’)),’#',”) as integer ) as num from t1
五十八、更改累计和中的值
db2/oracle
select case when trx=’PY’ then ‘PAYMENT’ else ‘PURCHASE’ end trx_type,amt,sum(case when
trx=’PY’ then -amt else amt end) over (order by id,amt) as balance from V
mysql/postgresql/sqlserver
select case when v1.trx=’PY’ then ‘PAYMENT’ else ‘PURCHASE’ end as trx_type,v1.amt,(select sum(case when v2.trx=’PY’ then -v2.amt else v2.amt end) from V v2 where v2.id< =v1.id) as balance from V v1
五十九、增加或减少日，月，年
db2
select hiredate -5 day as hd_minus_5D,hiredate +5 day as hd_plus_5D,hiredate -5 month as
hd_minus_5M,hiredate +5 month as hd_plus_5M,hiredate -5 year as hd_minus_5Y,hiredate +5 year
as hd_plus_5Y from emp where deptno=10
oracle
select hiredate-5 as hd_minus_5D,hiredate+5 as hd_plus_5D,add_months(hiredate,-5) as
hd_minus_5M,add_months(hiredate,5) as hd_plus_5M,add_months(hiredate,-5*12) as
hd_minus_5Y,add_months(hiredate,5*120 as hd_plus_5Y from emp where deptno=10
postgresql
select hiredate-interval '5 day' as hd_minus_5D,hiredate+interval '5 day' as
hd_plus_5D,hiredate-interval '5 month' as hd_minus_5M,hiredate+interval '5 month' as
hd_plus_5M,hiredate-interval '5 year' as hd_minus_5Y,hiredate+interval '5 year' as
hd_plus_5Y from emp where deptno=10
mysql
select hiredate-interval 5 day as hd_minus_5D,hiredate+interval 5 day as
hd_plus_5D,hiredate-interval 5 month as hd_minus_5M,hiredate+interval 5 month as
hd_plus_5M,hiredate-interval 5 year as hd_minus_5Y,hiredate+interval 5 year as hd_plus_5Y
from emp where deptno=10
select date_add(hiredate,interval -5 day) as hd_minus_5D,date_add(hiredate,interval 5 day)
as hd_plus_5D,date_add(hiredate,interval -5 month) as hd_minus_5M,date_add(hiredate,interval
5 month) as hd_plus_5M,date_add(hiredate,interval -5 year) as hd_minus_5Y,date_add
(hiredate,interval 5 year) as hd_plus_5Y from emp where deptno=10
sqlserver
select dateadd(day,-5,hiredate) as hd_minus_5D,dateadd(day,5,hiredate0 as
hd_plus_5D,dateadd(month,-5,hiredate) as hd_minus_5M,dateadd(month,5,hiredate) as
hd_plus_5M,dateadd(year,-5,hiredate) as hd_minus_5Y,dateadd(year,5,hiredate) as hd_plus_5Y
from emp where deptno=10
六十、计算2个日期之间的天数
db2
select days(ward_hd) - days(allen_hd) from (select hiredate as ward_hd from emp where
ename='WARD') x,(select hiredate as allen_hd from emp where ename='ALLEN') y
oracle/postgresql
select ward_hd - allen_hd from (select hiredate as ward_hd from emp where ename='WARD') x,
(select hiredate as allen_hd from emp where ename='ALLEN') y
mysql/sqlserver
select datediff(day,allen_hd,ward_hd) from select hiredate as ward_hd from emp where ename =
'WARD') x,(select hiredate as allen_hd from emp where ename='ALLEN') y
六十一、计算2个日期之间的工作日天数
db2
select sum(case when dayname(jones_hd+t500.id day -1 day) in ('Saturday','Sunday') then 0
else 1 end) as days from (select max(case when ename='BLAKE' then hiredate end) as
blake_hd,max(case when ename='JONES' then hiredate end) as jones_hd from emp where ename in
('BLAKE','JONES') ) x,t500 where t500.id <=blake_hd-jones_hd+1
mysql
select sum(case when date_format(date_add(jones_hd,interval t500.id-1 DAY),'%a') in
('Sat','Sun') then 0 else 1 end) as days from (select max(case when ename='BLAKE' then
hiredate end) as blake_hd,max(case when ename='JONES' then hiredate end) as jones_hd from
emp where ename in ('BLAKE','JONES') ) x,t500 where t500.id<=datediff(blake_hd,jones_hd)+1
oracle
select sum(case when to_char(jones_hd+t500.id-1,'DY') in ('SAT','SUN') then 0 else 1 end) as
days from ( select max(case when ename='BLAKE' then hiredate end ) as blake_hd,max(case when
ename='JONES' then hiredate end) as jones_hd from emp where ename in ('BLAKE','JONES') )
x,t500 where t500.id<=blake_hd-jones_hd+1
postgresql
select sum(case when trim(to_char(jones_hd+t500.id-1,'DAY')) in ('SATURDAY','SUNDAY') then 0
else 1 end) as days from (select max(case when ename='BLAKE' then hiredate end) as
blake_hd,max(case when ename='JONES' then hiredate end) as jones_hd from emp where ename in
('BLAKE','JONES') ) x,t500 where t500.id<=blake_hd-jones_hd+1
sqlserver
select sum(case when datename(dw,jones_hd+t500.id-1) in ('SATURDAY','SUNDAY') then 0 else 1
end) as days from ( select max(case when ename='BLAKE' then hiredate end) as blake_hd,max
(case when ename='JONES' then hiredate end) as jones_hd from emp where ename in
('BLAKE','JONES') ) x,t500 where t500.id<=datediff(day,jones_hd-blake_hd)+1
六十二、计算2个日期之间的月和年
db2/mysql
select mnth,mnth/12 from (select (year(max_hd)-year(min_hd))*12+(month(max_hd)-month
(min_hd)) as mnth from (select min(hiredate) as min_hd,max(hiredate) as max_hd from emp ) x
) y
oracle
select months_between(max_hd,min_hd),months_between(max_hd,min_hd)/12 from (select min
(hiredate) min_hd,max(hiredate) max_hd from emp ) x
postgresql
select mnth,mnth/12 from ( select extract(year from max_hd) extract(year from min_hd))*12 +
(extract(month from max_hd) extract(month from min_hd)) as mnth from (select min(hiredate)
as min_hd,max(hiredate) as max_hd from emp ) x ) y
sqlserver
select datediff(month,min_hd,max_hd),datediff(month,min_hd,max_hd)/12 from (select min
(hiredate) min_hd,max(hiredate) max_hd from emp ) x
六十三、计算2个日期之间的秒、分、小时
db2
select dy*24 hr,dy*24*60 min,day*24*60*60 sec from (select (days(max(case when ename='WARD'
then hiredate end))-days(max(case when ename='ALLEN' then hiredate end)) ) as dy from emp )
x
mysql/sqlserver
select datediff(day,allen_hd,ward_hd)*24 hr,datediff(day,allen_hd,ward_hd)*24*60
min,datediff(day,allen_hd,ward_hd)*24*60*60 sec from (select max(case when ename='WARD' then
hiredate end) as ward_hd,max(case when ename='ALLEN' then hiredate end) as allen_hd from emp
) x
oracle/postgresql
select dy*24 as hr,dy*24*60 as min,dy*24*60*60 as sec from (select (max(case when
ename='WARD' then hiredate end)-max(case when ename='ALLEN' then hiredate end)) as dy from
emp ) x
六十四、统计一年中的周日的天数
db2
with x (start_date,end_date) as ( select start_date,start_date+1 year end_date from (select
(current_date dayofyear(current_date) day)+1 day as start_date from t1) tmp union all select
start_date+1 day,end_date from x where start_date+1 day (start_date),count(*) from x group by dayname(start_date)
mysql
select date_format(date_add(cast(concat(year(current_date),'-01-01') as date),interval
t500.id-1 day),'%W') day,count(*) from t500 where t500.id<=datediff(cast(concat(year
(current_date)+1,'-01-01') as date),cast(concat(year(current_date),'-01-01') as date)) group
by date(format(date_add(cast(concat(year(current_date),'-01-01') as date),interval t500.id-1
day),'%W')
oracle
with x as (select level lvl from dual connect by level<=(add_months(trunc(sysdate,'y'),12)-
trunc(sysdate,'y'))) select to_char(trunc(sysdate,'y')+lvl-1,'DAY'),count(*) from x group by
to_char(trunc(sysdate,'y')+lvl-1,'DAY')
select to_char(trunc(sysdate,'y')+rownum-1,'DAY'),count(*) from t500 where rownum<=
(add_months(trunc(sysdate,'y'),12)-trunc(sysdate,'y')) group by to_char(trunc(sysdate,'y')
+rownum-1,'DAY')
postgresql
select to_char(cast(date_trunc('year',current_date) as date+gs.id-1,'DAY'),count(*) from
generate_series(1,366) gs(id) where gs.id<=(cast(date_trunc('year',current_date)+interval
'12 month' as date)-cast(date_trunc('year',current_date) as date)) group by to_char(cast
(date_trunc('year',current_date) as date) + gs.id-1,'DAY')
sqlserver
with x (start_date,end_date) as (select start_date,dateadd(year,1,start_date) end_date from
(select cast(cast(year(getdate()) as varchar) +'-01-01' as datetime) start_date from t1 )
tmp union all select dateadd(day,1,start_date),end_date from x where dateadd
(day,1,start_date) datename(dw,start_date) OPTION (MAXRECURSION 366)
六十五、查看2个记录之间的日期不同
db2
select x.*,days(x.next_hd)-days(x.hiredate) diff from (select e.deptno,e.name,e.hiredate,
(select min(d.hiredate) from emp d where d.hiredate>e.hiredate) next_hd from emp e where
e.deptno=10) x
mysql/sqlserver
select x.*,datediff(day,x.hiredate,x.next_hd) diff from (select
e.deptno,e.ename,e.hiredate,(select min(d.hiredate) from emp d where d.hiredate>e.hiredate)
next_hd from emp e where e.deptno=10 ) x
oracle
select ename,hiredate,next_hd,next_hd-hiredate diff from (select deptno,ename,hiredate,lead
(hiredate) over(order by hiredate) next_hd from emp ) where deptno=10
postgresql
select x.*,x.next_hd-x.hiredate as diff from (select e.deptno,e.ename,e.hiredate,(select
min(d.hiredate) from emp d where d.hiredate>e.hiredate) as next_hd from emp e where
e.deptno=10 ) x
六十六、判断这一年是不是闰年
db2
with x (dy,mth) as ( select dy,month(dy) from (select (current_date-dayofyear(current_date)
days+1 days)+1 months as dy from t1) tmp1 union all select dy+1 days,mth from x where month
(dy+1 day)=mth) select max(day(dy) from x
oracle
select to_char(last_day(add_months(trunc(sysdate,’y'),1)),’DD’) from t1
postgresql
select max(to_char(tmp2.dy+x.id,’DD’)) as dy from ( select dy,to_char(dy,’MM’) as mth from
(select cast(cast(date_trunc(’year’,current_date) as date)+interval ‘1 month’ as date) as dy
from t1) tmp1 ) tmp2,generate_series (0,29) x(id) where to_char(tmp2.dy+x.id,’MM’)=tmp2.mth
mysql
select day(last_day(date_add(date_add(date_add(current_date,interval -dayofyear
(current_date) day),interval 1 day),interval 1 month))) dy from t1
sqlserver
with x (dy,mth) as (select dy,month(dy) from (select dateadd(mm,1,(getdate()-datepart
(dy,getdate()))+1) dy from t1) tmp1 union all select dateadd(dd,1,dy),mth from x where
month(dateadd(dd,1,dy))=mth) select max(day(dy)) from x
六十七、计算这一年中有多少天
db2
select days((curr_year+1 year))-days(curr_year) from (select (current_date-dayofyear
(current_date) day+1 day) curr_year from t1 ) x
oracle
select add_months(trunc(sysdate,’y'),12)-trunc(sysdate,’y') from dual
postgresql
select cast((curr_year+interval ‘1 year’) as date) - curr_year from ( select cast
(date_trunc(’year’,current_date) as date) as curr_year from t1 ) x
mysql
select datediff((curr_year+interval 1 year),curr_year) from ( select adddate(current_date,-
dayofyear(current_date)+1) curr_year from t1 ) x
sqlserver
select datediff(d,curr_year,dateadd(yy,1,curr_year)) from ( select dateadd(d,-datepart
(dy,getdate())+1,getdate()) curr_year from t1 ) x
六十八、分解日期—-小时、分、秒、日、月、年
db2
select hour(current_timestamp) hr,minute(current_timestamp) min,second(current_timestamp)
sec,day(current_timestamp) dy,month(current_timestamp) mth,year(current_timestamp) yr from
t1
oracle
select to_number(to_char(sysdate,’hh24′)) hour,to_number(to_char(sysdate,’mi’))
min,to_number(to_char(sysdate,’ss’)) sec,to_number(to_char(sysdate,’dd’)) day,to_number
(to_char(sysdate,’mm’)) mth,to_number(to_char(sysdate,’yyyy’)) year from dual
postgresql
select to_number(to_char(current_timestamp,’hh24′),’99′) as hr,to_number(to_char
(current_timestamp,’mi’),’99′) as min,to_number(to_char(current_timestamp,’ss’),’99′) as
sec,to_number(to_char(current_timestamp,’dd’),’99′) as day,to_number(to_char
(current_timestamp,’mm’),’99′) as mth,to_number(to_char(current_timestamp,’yyyy’),’9999′) as
yr from t1
mysql
select date_format(current_timestamp,’%k’) hr,date_format(current_timestamp,’%i’)
min,date_format(current_timestamp,’%s’) sec,date_format(current_timestamp,’%d’)
dy,date_format(current_timestamp,’%m’) mon,date_format(current_timestamp,’%Y’) yr from t1
sqlserver
select datepart(hour,getdate()) hr,datepart(minute,getdate()) min,datepart(second,getdate())
sec,datepart(day,getdate()) dy,datepart(month,getdate()) mon,datepart(year,getdate()) yr
from t1
六十九、计算一个月的第一天和最后一天
db2
select (current_date-day(current_date) day+1 day) firstday,(current_date+1 month -day
(current_date) day) lastday from t1
oracle
select trunc(sysdate,’mm’) firstday,last_day(sysdate) lastday from dual
postgresql
select firstday,cast(firstday+interval ‘1 month’-interval ‘1 day’ as date) as lastday from (
select cast(date_trunc(’month’,current_date) as date) as firstday from t1) x
mysql
select date_add(current_date,interval -day(current_date)+1 day) firstday,last_day
(current_date) lastday from t1
sqlserver
select dateadd(day,-day(getdate())+1,getdate()) firstday,dateadd(day,-day(getdate(),dateadd
(month,1,getdate())) lastdate from t1
七十、计算出一年中的一周中某一天的日期
db2
with x (dy,yr) as ( select dy,year(dy) yr from (select (current_date-dayofyear(current_date)
days +1 days) as dy from t1) tmp1 union all select dy+1 days,yr from x where year(dy+1 day)
=yr) select dy from x where dayname(dy)=’Friday’
oracle
with x as (select trunc(sysdate,’y')+level-1 dy from dual connect by level< =add_months(trunc(sysdate,'y'),12)-trunc(sysdate,'y')) select * from x where to_char(dy-1,'d') ='5'
postgresql
select cast(date_trunc('year',current_date) as date)+x.id as dy from generate_series( 0,
(select cast(cast(date_trunc('year',current_date) as date) + interval '1 years' as date)-
cast(date_trunc('year',current_date) as date))-1 ) x(id) where to_char(cast(date_trunc
('year',current_date) as date)+x.id,'dy')='fri'
mysql
select dy from (select adddate(x.dy,interval t500.id-1 day) dy from (select dy,year(dy) yr
from (select adddate(adddate(current_date,interval -dayofyear(current_date) day),interval 1
day ) dy from t1) tmp1 ) x,t500 where year(adddate(x.dy,interval t500.id-1 day))=x.yr) tmp2
where dayname(dy)='Friday'
sqlserver
with x (dy,yr) as ( select dy,year(dy) yr from ( select getdate()-datepart(dy,getdate())+1
dy from t1) tmp1 union all select dateadd(dd,1,dy),yr from x where year(dateadd(dd,1,dy))
=yr) select x.dy from x where datename(dw,x.dy)='Friday' option (maxrecursion 400)
七十一、确定这个月中的第一次出现和最后一次出现的特定的周末
db2
with x (dy,mth,is_monday) as ( select dy,month(dy),case when dayname(dy)='Monday' then 1
else 0 end from (select (current_date-day(current_date) day +1 day) dy from t1) tmp1 union
all select (dy +1 day),mth,case when dayname(dy +1 day)='Monday' then 1 else 0 end from x
where month(dy +1 day)=mth) select min(dy) first_month,max(dy) last_monday from x where
is_monday=1
oracle
select next_day(trunc(sysdate,'mm')-1,'星期一') first_monday,next_day(last_day(trunc
(sysdate,'mm'))-7,'星期一') last_monday from dual
postgresql
select first_monday,case to_char(first_monday+28,'mm') when mth then first_monday+28 else
first_monday+21 end as last_monday from (select case sign(cast(to_char(dy,'d') as integer)
-2) when 0 then dy when -1 then dy+abs(cast(to_char(dy,'d') as integer)-2) when 1 then (7-
(cast(to_char(dy,'d') as integer)-2))+dy end as first_monday,mth from (select cast
(date_trunc('month',current_date) as date) as dy,to_char(current_date,'mm') as mth from t1 )x ) y
mysql
select first_monday,case month(adddate(first_monday,28)) when mth then adddate
(first_monday,28) else adddate(first_monday,21) end last_monday from ( select case sign
(dayofweek(dy)-2) when 0 then dy when -1 then adddate(dy,abs(dayofweek(dy)-2)) when 1 then adddate(dy,(7-(dayofweek(dy)-2))) end first_monday,mth from (select adddate(adddate
(current_date,-day(current_date)),1) dy,month(current_date0 mth from t1) x ) y
sqlserver
with x (dy,mth,is_monday) as ( select dy,mth,case when datepart(dw,dy)=2 then 1 else 0 end
from (select dateadd(day,1,dateadd(day,-day(getdate()),getdate())) dy,month(getdate()) mth
from t1 ) tmp1 union all select dateadd(day,1,dy),mth,case when datepart(dw,dateadd
(day,1,dy))=2 then 1 else 0 end from x where month(dateadd(day,1,dy))=mth ) select min(dy)
first_monday,max(dy) last_monday from x where is_monday=1
七十二、创建一个日历
db2
with x (dy,dm,mth,dw,wk) as ( select (current_date -day(current_date) day +1 day) dy,day
((current_date -day(current_date) day +1 day)) dm,month(current_date) mth,dayofweek
(current_date -day(current_date) day +1 day) dw,week(iso(current_date -day(current_date) day+1 day) wk from t1 union all select dy+1 day,day(dy+1 day),mth,dayofweek(dy+1 day),week_iso(dy+1 day) from x where month(dy+1 day)=mth ) select max(case dw when 2 then
dm end) as Mo,max(case dw when 3 then dm end) as Tu,max(case dw when 4 then dm end) as We,max(case dw when 5 then dm end) as Th,max(case dw when 6 then dm end) as Fr,max(case dw when 7 then dm end) as Sa,max(case dw when 1 then dm end) as Su from x group by
wk order by wk
oracle
with x as ( select * from (select to_char(trunc(sysdate,'mm')+level-1,'iw') wk,to_char
(trunc(sysdate,'mm')+level-1,'dd') dm,to_number(to_char(trunc(sysdate,'mm')+level-1,'d'))
dw,to_char(trunc(sysdate,'mm')+level-1,'mm') curr_mth,to_char(sysdate,'mm') mth from dual
connect by level<=31) where curr_mth<=31) select max(case dw when 2 then dm end) as Mo,max(case dw when 3 then dm end) as Tu,max(case dw when 4 then dm end) as We,max(case dw when 5 then dm end) as Th,max(case dw when 6 then dm end) as Fr,max(case dw when 7
then dm end) as Sa,max(case dw when 1 then dm end) as Su from x group by wk order by wk
postgresql
select max(case dw when 2 then dm end) as Mo,max(case dw when 3 then dm end) as Tu,max(case dw when 4 then dm end) as We,max(case dw when 5 then dm end) as Th,max(case dw when 6 then dm end) as Fr,max(case dw when 7 then dm end) as Sa,max(case dw when 1 then
dm end) as Su from (select * from ( select cast(date_trunc('month',current_date) as date) +x.id,to_char(cast(date_trunc('month',current_date0 as date)+x.id,'iw') as wk,to_char(cast(date_trunc('month',current_date) as date) +x.id,'dd') as dm,cast(to-char(cast(date_trunc('month',current_date)
as date) +x.id,'d') as integer) as dw,to_char(cast(date_trunc('month',current_date) as date) +x.id,'mm') as curr_mth,to_char(current_date,'mm') as mth
from generate_series (0,31) x(id) ) x where mth=curr_mth ) y group by wk order by wk
mysql
select max(case dw when 2 then dm end) as Mo,max(case dw when 3 then dm end) as Tu,max(case dw when 4 then dm end) as We,max(case dw when 5 then dm end) as Th,max(case dw when 6 then dm end) as Fr,max(case dw when 7 then dm end) as Sa,max(case dw when 1 then
dm end) as Su from (select date_format(dy,'%u') wk,date_format(dy,'%d') dm,date_format(dy,'%w')+1 dw from (select adddate(x.dy,t500.id-1) dy,x.mth from (select adddate(current_date,-dayofmonth(current_date)+1) dy,date_format(adddate(current_date,-dayomonth(current_date)+1),'%m')
mth from t1) x,t500 where t500.id<=31 and date_format(adddate(x.dy,t500.id-1),'%m')=x.mth) y ) z group by wk order by wk
sqlserver
with x (dy,dm,mth,dw,wk) as ( select dy,day(dy) dm,datepart(m,dy) mth,datepart(dw,dy)
dw,case when datepart(dw,dy)+1 then datepart(ww,dy)-1 else datepart(ww,dy) end wk from
(select dateadd(day,-day(getdate())+1,getdate()) dy from t1 ) x union all select dateadd
(d,1,dy),day(dateadd(d,1,dy)),mth,datepart(dw,dateadd(d,1,dy)),case when datepart
(dw,dateadd(d,1,dy))=1 then datepart(wk,dateadd(d,1,dy))-1 else datepart(wk,dateadd(d,1,dy)) end from x where datepart(m,dateadd(d,1,dy))=mth) select max(case dw when 2 then dm end) as Mo,max(case dw when 3 then dm end) as Tu,max(case dw when 4 then dm end)
as We,max(case dw when 5 then dm end) as Th,max(case dw when 6 then dm end) as Fr,max(case dw when 7 then dm end) as Sa,max(case dw when 1 then dm end) as Su from x group by wk order by wk
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