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num_field number(12,2);
±íʾnum_fieldÊÇÒ»¸öÕûÊý²¿·Ö×î¶à10λ¡¢Ð¡Êý²¿·Ö×î¶à2λµÄ±äÁ¿¡£
case.....when Ó÷¨£¨Óëdecode£¨£©×÷ÓúÜÏñ£©
select case zsxm_dm
when '02' then
'Ӫҵ˰'
when '09' then
'Ó¡»¨Ë°'
else
'ÎÞ˰ÖÖ'
end
from t_dm_gy_zsxm;
decode()º¯ÊýʹÓü¼ÇÉ
decode(Ìõ¼þ,Öµ1,·ÒëÖµ1,Öµ2,·ÒëÖµ2,...Öµn,·ÒëÖµn,ȱʡֵ)
¡¡¸Ãº¯ÊýµÄº¬ÒåÈçÏÂ:
¡¡¡¡IF Ìõ¼þ=Öµ1 THEN
¡¡¡¡RETURN(·ÒëÖµ1)
¡¡¡¡ELSIF Ìõ¼þ=Öµ2 THEN
¡¡¡¡RETURN(·ÒëÖµ2)
¡¡¡¡......
¡¡¡¡ELSIF Ìõ¼þ=Öµn THEN
¡¡¡¡RETURN(·ÒëÖµn)
¡¡¡¡ELSE
¡¡¡¡RETURN(ȱʡֵ)
¡¡¡¡END IF
sign()º¯Êý¸ù¾Ýij¸öÖµÊÇ0¡¢ÕýÊý»¹ÊǸºÊý£¬·Ö±ð·µ»Ø0¡¢1¡¢-1
±È½Ï´óС
select decode(sign(±äÁ¿1-±äÁ¿2),-1,±äÁ¿1,±äÁ¿2) from dual; --È¡½ÏСֵ
sign()º¯Êý¸ù¾Ýij¸öÖµÊÇ0¡¢ÕýÊý»¹ÊǸºÊý£¬·Ö±ð·µ»Ø0¡¢1¡¢-1
trunc(pz.xs_rq) ÊÇÖ¸Ö»ÒªÄêÔÂÈÕ£¬²»ÒªÊ±·ÖÃë
¶ÔÈÕÆÚ°´¸ñʽ½ØÎ²£¬Èç:SQL> select trunc(sysdate,'mm') from dual;
TRUNC(SYSDATE,'MM')
-------------------
2003-1-1
truncʵ¼ÊÉÏÊÇtruncateº¯Êý£¬×ÖÃæÒâ˼Êǽضϣ¬½ØÎ²¡£º¯ÊýµÄ¹¦ÄÜÊǽ«Êý×Ö½øÐнضϡ£ÀýÈç tranc(1234.5678,2)µÄ½á¹ûΪ1234.5600¡£tranc()²¢²»ËÄÉáÎåÈë¡£ÔÙ¾ÙÀý£º tranc(1234.5678,0)µÄ½á¹ûΪ1234.0000£»tranc(1234.5678,-2)µÄ½á¹ûΪ1200.0000¡£
EXISTS ¹Ø¼ü×ÖºÍ IN ¹Ø¼ü×ÖµÄÇø±ð£¿
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exists(select 1 from Table_B where Table_B.XH
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--¾ÛºÏº¯Êý
use pubs
go
select avg(distinct price) --ËãÆ½¾ùÊý
from titles
where type='business'
go
use pubs
go
select max(ytd_sales) --×î´óÊý
from titles
go
use pubs
go
select min(ytd_sales) --×îÐ¡Ê ......
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system/manager
sys/change_on_intall
scott/tiger
internal/oracle
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select name from V$database;
Çл»Á½¸ö ......
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isnull(check_expression,replacement_expression)
²ÎÊýcheck_expressionÓëreplacement_expressionÀàÐÍÐèÏàͬ
·µ»ØÖµ£º
Èôcheck_expressionΪnull£¬Ôò·µ»Øreplacement_expression
Èôcheck_expression²»Îªnull£¬Ôò·µ»Øcheck_expression ......