高手是怎樣煉成的 精妙SQL語句介紹

2021-04-14 06:14:35 字數 3311 閱讀 4489

說明:複製表(只複製結構,源表名:a 新錶名:b)  

sql: select * into b from a where 1<>1

說明:拷貝表(拷貝資料,源表名:a 目標表名:b)  

sql: insert into b(a, b, c) select d,e,f from b;

sql: select a.title,a.username,b.adddate from table a,(select max(adddate) adddate from table where table.title=a.title) b

說明:外連線查詢(表名1:a 表名2:b)  

sql: select a.a, a.b, a.c, b.c, b.d, b.f from a left out join b on a.a = b.c

sql: select * from 日程安排 where datediff('minute',f開始時間,getdate())>5  

說明:兩張關聯表,刪除主表中已經在副表中沒有的資訊

sql:   

delete from info where not exists ( select * from infobz where info.infid=infobz.infid

說明:--

sql:   

select a.num, a.name, b.upd_date, b.prev_upd_date

from table1,

(select x.num, x.upd_date, y.upd_date prev_upd_date

from (select num, upd_date, inbound_qty, stock_onhand

from table2

where to_char(upd_date,'yyyy/mm') = to_char(sysdate, 'yyyy/mm')) x,

(select num, upd_date, stock_onhand

from table2

where to_char(upd_date,'yyyy/mm') =

to_char(to_date(to_char(sysdate, 'yyyy/mm') ¦¦ '/01','yyyy/mm/dd') - 1, 'yyyy/mm') y,

where x.num = y.num (+)

and x.inbound_qty + nvl(y.stock_onhand,0) <> x.stock_onhand b

where a.num = b.num

說明:--

sql:   

select * from studentinfo where not exists(select * from student where studentinfo.id=student.id) and 系名稱='"&strdepartmentname&"' and 專業名稱='"&strprofessionname&"' order by 性別,生源地,高考總成績

說明:

從資料庫中去一年的各單位**費統計(**費定額賀電化肥清單兩個表**)

sql:  

select a.userper, a.tel, a.standfee, to_char(a.telfeedate, 'yyyy') as telyear,

sum(decode(to_char(a.telfeedate, '

mm'), '01', a.factration)) as jan,

sum(decode(to_char(a.telfeedate, 'mm'), '02', a.factration)) as fri,

sum(decode(to_char(a.telfeedate, 'mm'), '03', a.factration)) as mar,

sum(decode(to_char(a.telfeedate, 'mm'), '04', a.factration)) as apr,

sum(decode(to_char(a.telfeedate, 'mm'), '05', a.factration)) as may,

sum(decode(to_char(a.telfeedate, 'mm'), '06', a.factration)) as jue,

sum(decode(to_char(a.telfeedate, 'mm'), '07', a.factration)) as jul,

sum(decode(to_char(a.telfeedate, 'mm'), '08', a.factration)) as agu,

sum(decode(to_char(a.telfeedate, 'mm'), '09', a.factration)) as sep,

sum(decode(to_char(a.telfeedate, 'mm'), '10', a.factration)) as oct,

sum(decode(to_char(a.telfeedate, 'mm'), '11', a.factration)) as nov,

sum(decode(to_char(a.telfeedate, 'mm'), '12', a.factration)) as dec

from (select a.userper, a.tel, a.standfee, b.telfeedate, b.factration

from telfeestand a, telfee b

where a.tel = b.telfax) a

group by a.userper, a.tel, a.standfee, to_char(a.telfeedate, 'yyyy')

說明:四表聯查問題:  

sql: select * from a left inner join b on a.a=b.b right inner join c on a.a=c.c inner join d on a.a=d.d where .....

說明:得到表中最小的未使用的id號

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