43.CONVERT(c,dset,sset)
將源字符串 sset從一個(gè)語(yǔ)言字符集轉(zhuǎn)換到另一個(gè)目的dset字符集
SQL> select convert('strutz','we8hp','f7dec') "conversion" from dual;
conver
------
strutz
44.HEXTORAW 將一個(gè)十六進(jìn)制構(gòu)成的字符串轉(zhuǎn)換為二進(jìn)制
45.RAWTOHEXT 將一個(gè)二進(jìn)制構(gòu)成的字符串轉(zhuǎn)換為十六進(jìn)制
46.ROWIDTOCHAR 將ROWID數(shù)據(jù)類(lèi)型轉(zhuǎn)換為字符類(lèi)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') 將字符串轉(zhuǎn)化為ORACLE中的一個(gè)日期
49.TO_MULTI_BYTE? 將字符串中的單字節(jié)字符轉(zhuǎn)化為多字節(jié)字符
SQL>? select to_multi_byte('高') from dual;
TO
--
高
50.TO_NUMBER
將給出的字符轉(zhuǎn)換為數(shù)字
SQL> select to_number('1999') year from dual;
YEAR
---------
1999
51.BFILENAME(dir,file)指定一個(gè)外部二進(jìn)制文件
SQL>insert into file_tb1 values(bfilename('lob_dir1','image1.gif'));
52.CONVERT('x','desc','source') 將x字段或變量的源source轉(zhuǎn)換為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函數(shù)以fmt指定的內(nèi)部數(shù)字格式返回一個(gè)VARCHAR2類(lèi)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()
這兩個(gè)函數(shù)都是用來(lái)對(duì)大數(shù)據(jù)類(lèi)型字段進(jìn)行初始化操作的函數(shù)
55.GREATEST
返回一組表達(dá)式中的最大值,即比較字符的編碼大小.
SQL> select greatest('AA','AB','AC') from dual;
GR
--
AC
SQL> select greatest('啊','安','天') from dual;
GR
--
天
56.LEAST
返回一組表達(dá)式中的最小值
SQL> select least('啊','安','天') from dual;
LE
--
啊
57.UID
返回標(biāo)識(shí)當(dāng)前用戶的唯一整數(shù)
SQL> show user
USER 為"GAO"
SQL> select username,user_id from dba_users where user_id=uid;
USERNAME???????????????????????? USER_ID
------------------------------ ---------
GAO?????????????????????????????????? 25
58.USER
返回當(dāng)前用戶的名字
SQL> select user from? dual;
USER
------------------------------
GAO
59.USEREVN
返回當(dāng)前用戶環(huán)境的信息,opt可以是:
ENTRYID,SESSIONID,TERMINAL,ISDBA,LABLE,LANGUAGE,CLIENT_INFO,LANG,VSIZE
ISDBA? 查看當(dāng)前用戶是否是DBA如果是則返回true
SQL> select userenv('isdba') from dual;
USEREN
------
FALSE
SQL> select userenv('isdba') from dual;
USEREN
------
TRUE
SESSION
返回會(huì)話標(biāo)志
SQL> select userenv('sessionid') from dual;
USERENV('SESSIONID')
--------------------
152
ENTRYID
返回會(huì)話人口標(biāo)志
SQL> select userenv('entryid') from dual;
USERENV('ENTRYID')
------------------
0
INSTANCE
返回當(dāng)前INSTANCE的標(biāo)志
SQL> select userenv('instance') from dual;
USERENV('INSTANCE')
-------------------
1
LANGUAGE
返回當(dāng)前環(huán)境變量
SQL> select userenv('language') from dual;
USERENV('LANGUAGE')
----------------------------------------------------
SIMPLIFIED CHINESE_CHINA.ZHS16GBK
LANG
返回當(dāng)前環(huán)境的語(yǔ)言的縮寫(xiě)
SQL> select userenv('lang') from dual;
USERENV('LANG')
----------------------------------------------------
ZHS
TERMINAL
返回用戶的終端或機(jī)器的標(biāo)志
SQL> select userenv('terminal') from dual;
USERENV('TERMINA
----------------
GAO
VSIZE(X)
返回X的大小(字節(jié))數(shù)
SQL> select vsize(user),user from dual;
VSIZE(USER) USER
----------- ------------------------------
6 SYSTEM
60.AVG(DISTINCT|ALL)
all表示對(duì)所有的值求平均值,distinct只對(duì)不同的值求平均值
SQLWKS> create table table3(xm varchar(8),sal number(7,2));
語(yǔ)句已處理。
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
61.MAX(DISTINCT|ALL)
求最大值,ALL表示對(duì)所有的值求最大值,DISTINCT表示對(duì)不同的值求最大值,相同的只取一次
SQL> select max(distinct sal) from scott.emp;
MAX(DISTINCTSAL)
----------------
5000
62.MIN(DISTINCT|ALL)
求最小值,ALL表示對(duì)所有的值求最小值,DISTINCT表示對(duì)不同的值求最小值,相同的只取一次
SQL> select min(all sal) from gao.table3;
MIN(ALLSAL)
-----------
1111.11
63.STDDEV(distinct|all)
求標(biāo)準(zhǔn)差,ALL表示對(duì)所有的值求標(biāo)準(zhǔn)差,DISTINCT表示只對(duì)不同的值求標(biāo)準(zhǔn)差
SQL> select stddev(sal) from scott.emp;
STDDEV(SAL)
-----------
1182.5032
SQL> select stddev(distinct sal) from scott.emp;
STDDEV(DISTINCTSAL)
-------------------
1229.951
64.VARIANCE(DISTINCT|ALL) 求協(xié)方差
SQL> select variance(sal) from scott.emp;
VARIANCE(SAL)
-------------
1398313.9
65.GROUP BY 主要用來(lái)對(duì)一組數(shù)進(jìn)行統(tǒng)計(jì)
SQL> select deptno,count(*),sum(sal) from scott.emp group by deptno;
DEPTNO? COUNT(*)? SUM(SAL)
--------- --------- ---------
10???????? 3????? 8750
20???????? 5???? 10875
30???????? 6????? 9400
66.HAVING? 對(duì)分組統(tǒng)計(jì)再加限制條件
SQL> select deptno,count(*),sum(sal) from scott.emp group by deptno having nt(*)>=5;
DEPTNO? COUNT(*)? SUM(SAL)
--------- --------- ---------
20???????? 5???? 10875
30???????? 6????? 9400
SQL> select deptno,count(*),sum(sal) from scott.emp having count(*)>=5 group by tno ;
DEPTNO? COUNT(*)? SUM(SAL)
--------- --------- ---------
20???????? 5???? 10875
30???????? 6????? 9400
67.ORDER BY? 用于對(duì)查詢到的結(jié)果進(jìn)行排序輸出
SQL> select deptno,ename,sal from scott.emp order by deptno,sal desc;
DEPTNO ENAME??????????? SAL
--------- ---------- ---------
10 KING??????????? 5000
10 CLARK?????????? 2450
10 MILLER????????? 1300
20 SCOTT?????????? 3000
20 FORD??????????? 3000
20 JONES?????????? 2975
20 ADAMS?????????? 1100
20 SMITH??????????? 800
30 BLAKE?????????? 2850
30 ALLEN?????????? 1600
30 TURNER????????? 1500
30 WARD??????????? 1250
30 MARTIN????????? 1250
30 JAMES??????????? 950