TO_DATE( )③

10.Next_day的用法51Testing软件测试网V'g4w `r~m
  Next_day(date, day)   
:f)Y m9J"E1O0  Monday-Sunday, for format code DAY
8x1]RGOI!H$t0  Mon-Sun, for format code DY
|i^T"M-q3a;W0  1-7, for format code D

m$}lX|'R011.select to_char(sysdate,'hh:mi:ss') TIME from all_objects51Testing软件测试网6b4T&d8ZgG
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  注意：第一条记录的TIME 与最后一行是一样的51Testing软件测试网L'ew^I&R"U@
  可以建立一个函数来处理这个问题
/w DMX#ly9C U5z8_0  create or replace function sys_date return date is51Testing软件测试网rQuXj
  begin
+B9jjk AICPQ0  return sysdate;51Testing软件测试网x Z'c1GzS'f
  end;51Testing软件测试网L1{(F'A'H,hUp@3E
  
(GJ&H~3w`k'P*CI+y*T0  select to_char(sys_date,'hh:mi:ss') from all_objects;

w(G^` v]dt0}012. 获得小时数         
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^(^[R0   SELECT EXTRACT(HOUR FROM TIMESTAMP '2001-02-16 2:38:40') from offer51Testing软件测试网qaiKD+t
   SQL>; select sysdate ,to_char(sysdate,'hh') from dual;51Testing软件测试网p-m5G-hSl JMiS
        51Testing软件测试网(N3uB'nf3xA*cQ-i
   SYSDATE TO_CHAR(SYSDATE,'HH')
q(|'F#E8[$nP0   -------------------- ---------------------51Testing软件测试网J#A)UM4W&?5o DP-X
   2003-10-13 19:35:21 0751Testing软件测试网 z4QPeUv{w
        
(o"K1t+ZZ IG0   SQL>; select sysdate ,to_char(sysdate,'hh24') from dual;
(cDr.GT7q0        51Testing软件测试网
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   SYSDATE TO_CHAR(SYSDATE,'HH24')
Ruu3~!Q_C0   -------------------- -----------------------51Testing软件测试网)ACL$xszI`N}/P
   2003-10-13 19:35:21 19
)q)J2rhb0        51Testing软件测试网
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   获取年月日与此类似51Testing软件测试网WQi'}k*M!p,K

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~B013.年月日的处理51Testing软件测试网 Hxu|4Q_`b
  select older_date,51Testing软件测试网xxP1cR#D!b5?Z}
           newer_date,51Testing软件测试网I?/o$r5qo&_
           years,
+y{+Ody
]C a0           months,51Testing软件测试网.K#f$L.ZN:S:yO
           abs(trunc(newer_date-add_months( older_date,years*12+months ))) days51Testing软件测试网i R4|}v1A2l
     from (select trunc(months_between( newer_date, older_date )/12) YEARS,51Testing软件测试网OmA Y8h*PHW1}
                  mod(trunc(months_between( newer_date, older_date )),12 ) MONTHS,51Testing软件测试网#w(]Lx[U S$[
                  newer_date,
,SN4J2IS)Y,b0                  older_date
el2lJ"|pB3w0           from ( select hiredate older_date,add_months(hiredate,rownum)+rownum newer_date from emp ));