精妙的SQL語句2

2021-04-12 22:08:52 字數 4311 閱讀 5404

1.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

2.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 a;

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

4.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 outer join b on a.a = b.c

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

6.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

7.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')

8.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 .....

9.說明:得到表中最小的未使用的id號

sql:

select (case when exists(select * from handle b where b.handleid = 1) then min(handleid) + 1 else 1 end) as handleid

from handle

where not handleid in (select a.handleid - 1 from handle a)

9.sql語句技巧

9.1、乙個sql語句的問題:行列轉換

select * from v_temp

上面的檢視結果如下:

user_name role_name

-------------------------

系統管理員 管理員

feng 管理員

feng 一般使用者

test 一般使用者

想把結果變成這樣:

user_name role_name

---------------------------

系統管理員 管理員

feng 管理員,一般使用者

test 一般使用者

***************==

== create table a_test(name varchar(20),role2 varchar(20))

insert into a_test values('李','管理員')

insert into a_test values('張','管理員')

insert into a_test values('張','一般使用者')

insert into a_test values('常','一般使用者')

create function join_str(@content varchar(100))

returns varchar(2000) as

begin

declare @str varchar(2000)

set @str=''

select @str=@str+','+rtrim(role2) from a_test where [name]=@content

select @str=right(@str,len(@str)-1)

return @str

end go

--呼叫:

select [name],dbo.join_str([name]) role2 from a_test group by [name]

--select distinct name,dbo.uf_test(name) from a_test

精妙SQL語句

精妙sql語句 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 複製表 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....

精妙Sql語句

1 判斷a 表中有而 b表中沒有的記錄 select a.from tbl1 a left join tbl2 b on a.key b.key where b.key is null 雖然使用 in也可以實現,但是這種方法的效率更高一些 2 新建乙個與某個表相同結構的表 select into b...

精妙SQL語句

1 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 2.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 3 select a.title,...