Oracle SQL 内置函数大全（二）

 

 

31.SIGH
返回双曲正弦的值
SQL> Select Sin(20),Sinh(20) From Dual;
SIN(20)  SINH(20)
--------- ---------
.91294525 242582598


32.SQRT
返回数字N的根
SQL> Select Sqrt(64),Sqrt(10) From Dual;

SQRT(64)  SQRT(10)
--------- ---------
8 3.1622777


33.TAN
返回数字的正切值
SQL> Select Tan(20),Tan(10) From Dual;

TAN(20)   TAN(10)
--------- ---------
2.2371609 .64836083


34.TANH
返回数字N的双曲正切值
SQL> Select Tanh(20),Tan(20) From Dual;

TANH(20)   TAN(20)
--------- ---------
1 2.2371609

 

35.TRUNC
按照指定的精度截取一个数
SQL> Select Trunc(124.1666,-2) Trunc1,Trunc(124.16666,2) From Dual;

TRUNC1 TRUNC(124.16666,2)
--------- ------------------
100             124.16

 

36.ADD_MONTHS
增加或减去月份
SQL> Select To_char(Add_months(To_date('199912','Yyyymm'),2),'Yyyymm') From Dual;

TO_CHA
------
200002
SQL> Select To_char(Add_months(To_date('199912','Yyyymm'),-2),'Yyyymm') From Dual;

TO_CHA
------
199910


37.LAST_DAY
返回日期的最后一天
SQL> Select To_char(Sysdate,'Yyyy.Mm.Dd'),To_char((Sysdate)+1,'Yyyy.Mm.Dd') From Dual;

TO_CHAR(SY TO_CHAR((S
---------- ----------
2004.05.09 2004.05.10
SQL> Select Last_day(Sysdate) From Dual;

LAST_DAY(S
----------
31-5月 -04


38.MONTHS_BETWEEN(Date2,Date1)
给出Date2-Date1的月份
SQL> Select Months_between('19-12月-1999','19-3月-1999') Mon_between From Dual;

MON_BETWEEN
-----------
  9
SQL>Selectmonths_between(To_date('2000.05.20','Yyyy.Mm.Dd'),To_date('2005.05.20','Yyyy.Dd')) Mon_betw From Dual;

MON_BETW
---------
-60


39.NEW_TIME(Date,'This','That')
给出在This时区=Other时区的日期和时间
SQL> Select To_char(Sysdate,'Yyyy.Mm.Dd Hh24:Mi:ss') Bj_time,To_char(New_time
2  (Sysdate,'PDT','GMT'),'Yyyy.Mm.Dd Hh24:Mi:ss') Los_angles From Dual;

BJ_TIME             LOS_ANGLES
------------------- -------------------
2004.05.09 11:05:32 2004.05.09 18:05:32


40.NEXT_DAY(Date,'Day')
给出日期Date和星期X之后计算下一个星期的日期
SQL> Select Next_day('18-5月-2001','星期五') Next_day From Dual;

NEXT_DAY
----------
25-5月 -01

 

41.SYSDATE
用来得到系统的当前日期
SQL> Select To_char(Sysdate,'Dd-Mm-Yyyy Day') From Dual;

TO_CHAR(SYSDATE,'
-----------------
09-05-2004 星期日
Trunc(Date,Fmt)按照给出的要求将日期截断,如果Fmt='Mi'表示保留分,截断秒
SQL> Select To_char(Trunc(Sysdate,'Hh'),'Yyyy.Mm.Dd Hh24:Mi:ss') Hh,
  2  To_char(Trunc(Sysdate,'Mi'),'Yyyy.Mm.Dd Hh24:Mi:ss') Hhmm From Dual;

HH                  HHMM
------------------- -------------------
2004.05.09 11:00:00 2004.05.09 11:17:00

 

42.CHARTOROWID
将字符数据类型转换为ROWID类型
SQL> Select Rowid,Rowidtochar(Rowid),Ename From Scott.Emp;

ROWID              ROWIDTOCHAR(ROWID) ENAME
------------------ ------------------ ----------
AAAAfKAACAAAAEqAAA AAAAfKAACAAAAEqAAA SMITH
AAAAfKAACAAAAEqAAB AAAAfKAACAAAAEqAAB ALLEN
AAAAfKAACAAAAEqAAC AAAAfKAACAAAAEqAAC WARD
AAAAfKAACAAAAEqAAD AAAAfKAACAAAAEqAAD JONES


43.CONVERT(C,Dset,Sset)
将源字符串 Sset从一个语言字符集转换到另一个目的Dset字符集
SQL> Select Convert('Strutz','We8hp','F7dec') "Conversion" From Dual;

Conver
------
Strutz


44.HEXTORAW
将一个十六进制构成的字符串转换为二进制


45.RAWTOHEXT
将一个二进制构成的字符串转换为十六进制

 

46.ROWIDTOCHAR
将ROWID数据类型转换为字符类型

 

47.TO_CHAR(Date,'Format')
SQL> Select To_char(Sysdate,'Yyyy/Mm/Dd Hh24:Mi:ss') From Dual;

TO_CHAR(SYSDATE,'YY
-------------------
2004/05/09 21:14:41

 

48.TO_DATE(String,'Format')
将字符串转化为ORACLE中的一个日期


49.TO_MULTI_BYTE
将字符串中的单字节字符转化为多字节字符
SQL>  Select To_multi_byte('高') From Dual;

TO
--
高


50.TO_NUMBER
将给出的字符转换为数字
SQL> Select To_number('1999') Year From Dual;

     YEAR
---------
     1999


51.BFILENAME(Dir,File)
指定一个外部二进制文件
SQL>Insert Into File_tb1 Values(Bfilename('Lob_dir1','Image1.Gif'));


52.CONVERT('X','Desc','Source')
将X字段或变量的源Source转换为Desc
SQL> Select Sid,Serial#,Username,Decode(Command,
  2  0,'None',
  3  2,'Insert',
  4  3,
  5  'Select',
  6  6,'Update',
  7  7,'Delete',
  8  8,'Drop',
  9  'Other') Cmd  From V$Session Where Type!='Background';

      SID   SERIAL# USERNAME                       CMD
--------- --------- ------------------------------ ------
        1         1                                None
        2         1                                None
        3         1                                None
        4         1                                None
        5         1                                None
        6         1                                None
        7      1275                                None
        8      1275                                None
        9        20 GAO                            Select
       10        40 GAO                            None


53.DUMP(S,Fmt,Start,Length)
DUMP函数以Fmt指定的内部数字格式返回一个VARCHAR2类型的值
SQL> Col Global_name For A30
SQL> Col Dump_string For A50
SQL> Set Lin 200
SQL> Select Global_name,Dump(Global_name,1017,8,5) Dump_string From Global_name;

GLOBAL_NAME                    DUMP_STRING
------------------------------ --------------------------------------------------
ORACLE.WORLD                   Typ=1 Len=12 CharacterSet=ZHS16GBK: W,O,R,L,D


54.EMPTY_BLOB()和EMPTY_CLOB()
这两个函数都是用来对大数据类型字段进行初始化操作的函数


55.GREATEST
返回一组表达式中的最大值,即比较字符的编码大小.
SQL> Select Greatest('AA','AB','AC') From Dual;

GR
--
AC
SQL> Select Greatest('啊','安','天') From Dual;

GR
--
天


56.LEAST
返回一组表达式中的最小值 
SQL> Select Least('啊','安','天') From Dual;

LE
--
啊


57.UID
返回标识当前用户的唯一整数
SQL> Show User
USER 为"GAO"
SQL> Select Username,User_id From Dba_users Where User_id=Uid;

USERNAME                         USER_ID
------------------------------ ---------
GAO                                   25

 

58.USER
返回当前用户的名字
SQL> Select User From  Dual;

USER
------------------------------
GAO


59.USEREVN
返回当前用户环境的信息,Opt可以是:
ENTRYID,SESSIONID,TERMINAL,ISDBA,LABLE,LANGUAGE,CLIENT_INFO,LANG,VSIZE
ISDBA  查看当前用户是否是DBA如果是则返回True
SQL> Select Userenv('Isdba') From Dual;

USEREN
------
FALSE
SQL> Select Userenv('Isdba') From Dual;

USEREN
------
TRUE
SESSION
返回会话标志
SQL> Select Userenv('Sessionid') From Dual;

USERENV('SESSIONID')
--------------------
                 152
ENTRYID
返回会话人口标志
SQL> Select Userenv('Entryid') From Dual;

USERENV('ENTRYID')
------------------
                 0
INSTANCE
返回当前INSTANCE的标志
SQL> Select Userenv('Instance') From Dual;

USERENV('INSTANCE')
-------------------
                  1
LANGUAGE
返回当前环境变量
SQL> Select Userenv('Language') From Dual;

USERENV('LANGUAGE')
----------------------------------------------------
SIMPLIFIED CHINESE_CHINA.ZHS16GBK
LANG
返回当前环境的语言的缩写
SQL> Select Userenv('Lang') From Dual;

USERENV('LANG')
----------------------------------------------------
ZHS
TERMINAL
返回用户的终端或机器的标志
SQL> Select Userenv('Terminal') From Dual;

USERENV('TERMINA
----------------
GAO
VSIZE(X)
返回X的大小(字节)数
SQL> Select Vsize(User),User From Dual;

VSIZE(USER) USER
----------- ------------------------------
          6 SYSTEM

 

60.AVG(DISTINCT|ALL)
All表示对所有的值求平均值,Distinct只对不同的值求平均值
SQLWKS> Create Table Table3(Xm Varchar(8),Sal Number(7,2));
语句已处理。
SQLWKS>  Insert Into Table3 Values('Gao',1111.11);
SQLWKS>  Insert Into Table3 Values('Gao',1111.11);
SQLWKS>  Insert Into Table3 Values('Zhu',5555.55);
SQLWKS> Commit;

SQL> Select Avg(Distinct Sal) From Gao.Table3;

AVG(DISTINCTSAL)
----------------
         3333.33

SQL> Select Avg(All Sal) From Gao.Table3;

AVG(ALLSAL)
-----------
    2592.59

 

 

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