SQL中的单记录函数
1.ASCII
返回与指定的字符对应的十进制数;
SQL> select ascii('A') A,ascii('a') a,ascii('0') zero,ascii(' ') space from dual;
A A ZERO SPACE
--------- --------- --------- ---------
65 97 48 32
2.CHR
给出整数,返回对应的字符;
SQL> select chr(54740) zhao,chr(65) chr65 from dual;
ZH C
-- -
赵 A
3.CONCAT
连接两个字符串;
SQL> select concat('010-','88888888')||'转23' 高乾竞电话 from dual;
高乾竞电话
----------------
010-88888888转23
4.INITCAP
返回字符串并将字符串的第一个字母变为大写;
SQL> select initcap('smith') upp from dual;
UPP
-----
Smith
5.INSTR(C1,C2,I,J)
在一个字符串中搜索指定的字符,返回发现指定的字符的位置;
C1 被搜索的字符串
C2 希望搜索的字符串
I 搜索的开始位置,默认为1
J 出现的位置,默认为1
SQL> select instr('oracle traning','ra',1,2) instring from dual;
INSTRING
---------
9
6.LENGTH
返回字符串的长度;
SQL> select name,length(name),addr,length(addr),sal,length(to_char(sal)) from gao.nchar_tst;
NAME LENGTH(NAME) ADDR LENGTH(ADDR) SAL LENGTH(TO_CHAR(SAL))
------ ------------ ---------------- ------------ --------- --------------------
高乾竞 3 北京市海锭区 6 9999.99 7
7.LOWER
返回字符串,并将所有的字符小写
SQL> select lower('AaBbCcDd')AaBbCcDd from dual;
AABBCCDD
--------
aabbccdd
8.UPPER
返回字符串,并将所有的字符大写
SQL> select upper('AaBbCcDd') upper from dual;
UPPER
--------
AABBCCDD
9.RPAD和LPAD(粘贴字符)
RPAD 在列的右边粘贴字符
LPAD 在列的左边粘贴字符
SQL> select lpad(rpad('gao',10,'*'),17,'*')from dual;
LPAD(RPAD('GAO',1
-----------------
*******gao*******
不够字符则用*来填满
10.LTRIM和RTRIM
LTRIM 删除左边出现的字符串
RTRIM 删除右边出现的字符串
SQL> select ltrim(rtrim(' gao qian jing ',' '),' ') from dual;
LTRIM(RTRIM('
-------------
gao qian jing
11.SUBSTR(string,start,count)
取子字符串,从start开始,取count个
SQL> select substr('13088888888',3,8) from dual;
SUBSTR('
--------
08888888
12.REPLACE('string','s1','s2')
string 希望被替换的字符或变量
s1 被替换的字符串
s2 要替换的字符串
SQL> select replace('he love you','he','i') from dual;
REPLACE('H
----------
i love you
13.SOUNDEX
返回一个与给定的字符串读音相同的字符串
SQL> create table table1(xm varchar(8));
SQL> insert into table1 values('weather');
SQL> insert into table1 values('wether');
SQL> insert into table1 values('gao');
SQL> select xm from table1 where soundex(xm)=soundex('weather');
XM
--------
weather
wether
14.TRIM('s' from 'string')
LEADING 剪掉前面的字符
TRAILING 剪掉后面的字符
如果不指定,默认为空格符
15.ABS
返回指定值的绝对值
SQL> select abs(100),abs(-100) from dual;
ABS(100) ABS(-100)
--------- ---------
100 100
16.ACOS
给出反余弦的值
SQL> select acos(-1) from dual;
ACOS(-1)
---------
3.1415927
17.ASIN
给出反正弦的值
SQL> select asin(0.5) from dual;
ASIN(0.5)
---------
.52359878
18.ATAN
返回一个数字的反正切值
SQL> select atan(1) from dual;
ATAN(1)
---------
.78539816
19.CEIL
返回大于或等于给出数字的最小整数
SQL> select ceil(3.1415927) from dual;
CEIL(3.1415927)
---------------
4
20.COS
返回一个给定数字的余弦
SQL> select cos(-3.1415927) from dual;
COS(-3.1415927)
---------------
-1
21.COSH
返回一个数字反余弦值
SQL> select cosh(20) from dual;
COSH(20)
---------
242582598
22.EXP
返回一个数字e的n次方根
SQL> select exp(2),exp(1) from dual;
EXP(2) EXP(1)
--------- ---------
7.3890561 2.7182818
23.FLOOR
对给定的数字取整数
SQL> select floor(2345.67) from dual;
FLOOR(2345.67)
--------------
2345
24.LN
返回一个数字的对数值
SQL> select ln(1),ln(2),ln(2.7182818) from dual;
LN(1) LN(2) LN(2.7182818)
--------- --------- -------------
0 .69314718 .99999999
25.LOG(n1,n2)
返回一个以n1为底n2的对数
SQL> select log(2,1),log(2,4) from dual;
LOG(2,1) LOG(2,4)
--------- ---------
0 2
26.MOD(n1,n2)
返回一个n1除以n2的余数
SQL> select mod(10,3),mod(3,3),mod(2,3) from dual;
MOD(10,3) MOD(3,3) MOD(2,3)
--------- --------- ---------
1 0 2
27.POWER
返回n1的n2次方根
SQL> select power(2,10),power(3,3) from dual;
POWER(2,10) POWER(3,3)
----------- ----------
1024 27
28.ROUND和TRUNC
按照指定的精度进行舍入
SQL> select round(55.5),round(-55.4),trunc(55.5),trunc(-55.5) from dual;
ROUND(55.5) ROUND(-55.4) TRUNC(55.5) TRUNC(-55.5)
----------- ------------ ----------- ------------
56 -55 55 -55
29.SIGN
取数字n的符号,大于0返回1,小于0返回-1,等于0返回0
SQL> select sign(123),sign(-100),sign(0) from dual;
SIGN(123) SIGN(-100) SIGN(0)
--------- ---------- ---------
1 -1 0
30.SIN
返回一个数字的正弦值
SQL> select sin(1.57079) from dual;
SIN(1.57079)
------------
1
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.mm.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
61.MAX(DISTINCT|ALL)
求最大值,ALL表示对所有的值求最大值,DISTINCT表示对不同的值求最大值,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表示对所有的值求最小值,DISTINCT表示对不同的值求最小值,相同的只取一次
SQL> select min(all sal) from gao.table3;
MIN(ALLSAL)
-----------
1111.11
63.STDDEV(distinct|all)
求标准差,ALL表示对所有的值求标准差,DISTINCT表示只对不同的值求标准差
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)
求协方差
SQL> select variance(sal) from scott.emp;
VARIANCE(SAL)
-------------
1398313.9
65.GROUP BY
主要用来对一组数进行统计
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
对分组统计再加限制条件
SQL> select deptno,count(*),sum(sal) from scott.emp group by deptno having count(*)>=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 deptno ;
DEPTNO COUNT(*) SUM(SAL)
--------- --------- ---------
20 5 10875
30 6 9400
67.ORDER BY
用于对查询到的结果进行排序输出
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
-------------------------------------------------------------------------------------------------------------------------------------part2------------------------------------------------------------------------------------------------------------------------------------------
SQL >SELECT A.TABLESPACE_NAME,( 1 -(A.TOTAL)/B.TOTAL)* 100 USED_PERCENT
FROM (SELECT TABLESPACE_NAME,SUM (BYTES) TOTAL FROM DBA_FREE_SPACE GROUP BY TABLESPACE_NAME) A,(SELECT TABLESPACE_NAME,SUM (BYTES) TOTAL FROM DBA_DATA_FILES GROUP BY TABLESPACE_NAME) B WHERE A.TABLESPACE_NAME=B.TABLESPACE_NAME;
SQL >SELECT UPPER(F.TABLESPACE_NAME) " 表空间名 ",
D.TOT_GROOTTE_MB " 表空间大小 (M)",
D.TOT_GROOTTE_MB - F.TOTAL_BYTES " 已使用空间 (M)" , TO_CHAR(ROUND((D.TOT_GROOTTE_MB - F.TOTAL_BYTES) / D.TOT_GROOTTE_MB * 100 , 2 ), '990.99' ) " 使用比 ",F.TOTAL_BYTES" 空闲空间 (M) ",
F.MAX_BYTES " 最大块 (M) " FROM (SELECT TABLESPACE_NAME,
ROUND(SUM (BYTES) / ( 1024 * 1024 ), 2 ) TOTAL_BYTES,
ROUND(MAX (BYTES) / ( 1024 * 1024 ), 2 ) MAX_BYTES
FROM SYS .DBA_FREE_SPACE GROUP BY TABLESPACE_NAME) F,
(SELECT DD.TABLESPACE_NAME,ROUND(SUM (DD.BYTES) / ( 1024 * 1024 ), 2 ) TOT_GROOTTE_MB FROM SYS .DBA_DATA_FILES DD
GROUP BY DD.TABLESPACE_NAME) D WHERE D.TABLESPACE_NAME = F.TABLESPACE_NAME
ORDER BY 4 DESC ;
查看各个表空间占用磁盘情况 :
SQL >COL TABLESPACE_NAME FORMAT A20;
SQL >SELECT B.FILE_ID FILE_ID,
B.TABLESPACE_NAME TABLESPACE_NAME,
B.BYTES BYTES,
(B.BYTES-SUM (NVL(A.BYTES, 0 ))) USED,
SUM (NVL(A.BYTES, 0 )) FREE,
SUM (NVL(A.BYTES, 0 ))/(B.BYTES)* 100 PERCENT
FROM DBA_FREE_SPACE A,DBA_DATA_FILES B
WHERE A.FILE_ID=B.FILE_ID
GROUP BY B.TABLESPACE_NAME,B.FILE_ID,B.BYTES
ORDER BY B.FILE_ID;
数据库对象下一扩展与表空间的 free 扩展值的检查：
SQL >SELECT A.TABLE_NAME, A.NEXT_EXTENT, A.TABLESPACE_NAME
FROM ALL_TABLES A,(SELECT TABLESPACE_NAME, MAX (BYTES) AS BIG_CHUNK
FROM DBA_FREE_SPACE GROUP BY TABLESPACE_NAME ) F WHERE F.TABLESPACE_NAME = A.TABLESPACE_NAME AND A.NEXT_EXTENT > F.BIG_CHUNK
UNION SELECT A.INDEX_NAME, A.NEXT_EXTENT, A.TABLESPACE_NAME
FROM ALL_INDEXES A,(SELECT TABLESPACE_NAME, MAX (BYTES) AS BIG_CHUNK
FROM DBA_FREE_SPACE GROUP BY TABLESPACE_NAME ) F WHERE F.TABLESPACE_NAME = A.TABLESPACE_NAME AND A.NEXT_EXTENT > F.BIG_CHUNK;
Disk Read 最高的 SQL 语句的获取：
SQL >SELECT SQL_TEXT FROM (SELECT * FROM V$SQLAREA ORDER BY DISK_READS)
WHERE ROWNUM <= 5 ;
查找前十条性能差的 sql
SELECT * FROM (SELECT PARSING_USER_ID
EXECUTIONS,SORTS,COMMAND_TYPE,DISK_READS,
SQL_TEXT FROM V$SQLAREA ORDER BY DISK_READS DESC )
WHERE ROWNUM < 10 ;
等待时间最多的 5 个系统等待事件的获取：
SQL >SELECT * FROM (SELECT * FROM V$SYSTEM_EVENT WHERE EVENT NOT LIKE 'SQL%' ORDER BY TOTAL_WAITS DESC ) WHERE ROWNUM <= 5 ;
查看当前等待事件的会话 :
COL USERNAME FORMAT A10
SET LINE 120
COL EVENT FORMAT A30
SELECT SE.SID,S.USERNAME,SE.EVENT,SE.TOTAL_WAITS,SE.TIME_WAITED,SE.AVERAGE_WAIT
FROM V$SESSION S,V$SESSION_EVENT SE WHERE S.USERNAME IS NOT NULL AND SE.SID=S.SID
AND S.STATUS= 'ACTIVE' AND SE.EVENT NOT LIKE '%SQL*NET%' ;
SELECT SID, EVENT, P1, P2, P3, WAIT_TIME, SECONDS_IN_WAIT, STATE FROM V$SESSION_WAIT WHERE EVENT NOT LIKE'%MESSAGE%' AND EVENT NOT LIKE 'SQL*NET%' AND EVENT NOT LIKE '%TIMER%' AND EVENT != 'WAKEUP TIME MANAGER' ;
找到与所连接的会话有关的当前等待事件：
SELECT SW.SID,S.USERNAME,SW.EVENT,SW.WAIT_TIME,SW.STATE,SW.SECONDS_IN_WAIT SEC_IN_WAIT
FROM V$SESSION S,V$SESSION_WAIT SW WHERE S.USERNAME IS NOT NULL AND SW.SID=S.SID
AND SW.EVENT NOT LIKE '%SQL*NET%' ORDER BY SW.WAIT_TIME DESC ;
Oracle 所有回滚段状态的检查：
SQL>SELECT SEGMENT_NAME,OWNER,TABLESPACE_NAME,INITIAL_EXTENT,NEXT_EXTENT,DBA_ROLLBACK_SEGS.STATUS FROM DBA_ROLLBACK_SEGS,V$DATAFILE WHERE FILE_ID=FILE #;
Oracle 回滚段扩展信息的检查 :
COL NAME FORMAT A10
SET LINESIZE 140
SELECT SUBSTR(NAME , 1 , 40 ) NAME ,EXTENTS ,RSSIZE,OPTSIZE,AVEACTIVE,EXTENDS,WRAPS,SHRINKS,HWMSIZE
FROM V$ROLLNAME RN,V$ROLLSTAT RS WHERE (RN.USN=RS.USN);
EXTENTS : 回滚段中的盘区数量。
Rssize: 以字节为单位的回滚段的尺寸。
optsize ：为 optimal 参数设定的值。
Aveactive: 从回滚段中删除盘区时释放的以字节为单位的平均空间的大小。
Extends: 系统为回滚段增加的盘区的次数。
Shrinks: 系统从回滚段中清除盘区（即回滚段收缩）的次数。回滚段每次清除盘区时，系统可能会从这个回滚段中消除一个或多个盘区。
Hwmsize: 回滚段尺寸的上限，即回滚段曾经达到的最大尺寸。
( 如果回滚段平均尺寸接近 OPTIMAL 的值，那么说明 OPTIMAL 的值设置正确，如果回滚段动态增长次数或收缩次数很高，那么需要提高 OPTIMAL 的值 )
查看回滚段的使用情况，哪个用户正在使用回滚段的资源 :
SELECT S.USERNAME, U.NAME FROM V$TRANSACTION T,V$ROLLSTAT R,
V$ROLLNAME U,V$SESSION S WHERE S.TADDR=T.ADDR AND
T.XIDUSN=R.USN AND R.USN=U.USN ORDER BY S.USERNAME;
如何查看一下某个 shared_server 正在忙什么 :
SELECT A.USERNAME,A.MACHINE,A.PROGRAM,A.SID,
A.SERIAL#,A.STATUS,C.PIECE,C.SQL_TEXT
FROM V$SESSION A,V$PROCESS B,V$SQLTEXT C
WHERE B.SPID= 13161 AND B.ADDR=A.PADDR
AND A.SQL_ADDRESS=C.ADDRESS(+) ORDER BY C.PIECE;
数据库共享池性能检查 :
SELECT NAMESPACE,GETS,GETHITRATIO,PINS,PINHITRATIO,RELOADS,INVALIDATIONS FROM V$LIBRARYCACHE WHERE NAMESPACE IN ( 'SQLAREA' , 'TABLE/PROCEDURE' , 'BODY' , 'TRIGGER' );
检查数据重载比率 :
SELECT SUM (RELOADS)/SUM (PINS)* 100 "RELOAD RATIO" FROM
V$LIBRARYCACHE;
检查数据字典的命中率 :
SELECT 1 -SUM (GETMISSES)/SUM (GETS) "DATA DICTIONARY HIT
RATIO" FROM V$ROWCACHE;
( 对于 library cache, gethitratio 和 pinhitratio 应该大于 90%, 对于数据重载比率 ,reload ratio 应该小于 1%, 对于数据字典的命中率,data dictionary hit ratio 应该大于 85%)
检查共享内存的剩余情况 :
SELECT REQUEST_MISSES, REQUEST_FAILURES FROM V$SHARED_POOL_RESERVED;
( 对于共享内存的剩余情况 , request_misses 和 request_failures 应该接近 0)
数据高速缓冲区性能检查 :
SELECT 1 -P.VALUE /(B.VALUE +C.VALUE ) "DB BUFFER CACHE HIT RATIO" FROM V$SYSSTAT P,V$SYSSTAT B,V$SYSSTAT C WHERE P.NAME = 'PHYSICAL READS' AND B.NAME = 'DB BLOCK GETS' AND C.NAME = 'CONSISTENT GETS' ;
检查 buffer pool HIT_RATIO 执行
SELECT NAME , (PHYSICAL_READS/(DB_BLOCK_GETS+CONSISTENT_GETS)) "MISS_HIT_RATIO" FROM V$BUFFER_POOL_STATISTICS WHERE (DB_BLOCK_GETS+ CONSISTENT_GETS)> 0 ;
( 正常时 db buffer cache hit ratio 应该大于 90%, 正常时 buffer pool MISS_HIT_RATIO 应该小于 10%)
数据库回滚段性能检查 :
检查 Ratio 执行
SELECT SUM (WAITS)* 100 /SUM (GETS) "RATIO", SUM (WAITS) "WAITS", SUM (GETS) "GETS" FROM V$ROLLSTAT;
检查 count/value 执行 :
SELECT CLASS ,COUNT FROM V$WAITSTAT WHERE CLASS LIKE '%UNDO%' ;
SELECT VALUE FROM V$SYSSTAT WHERE NAME = 'CONSISTENT GETS' ;
( 两者的 value 值相除 )
检查 average_wait 执行 :
SELECT EVENT,TOTAL_WAITS,TIME_WAITED,AVERAGE_WAIT FROM V$SYSTEM_EVENT WHERE EVENT LIKE '%UNDO%' ;
检查 RBS header get ratio 执行 :
SELECT N.NAME ,S.USN,S.WRAPS, DECODE(S.WAITS, 0 , 1 , 1 - S.WAITS/S.GETS)"RBS HEADER GET RATIO" FROM V$ROLLSTAT S,V$ROLLNAME N WHERE S.USN=N.USN;
( 正常时 Ratio 应该小于 1%, count/value 应该小于 0.01%,average_wait 最好为 0 ，该值越小越好 ,RBS header get ratio 应该大于95%)
杀会话的脚本 :
SELECT A.SID,B.SPID,A.SERIAL#,A.LOCKWAIT,A.USERNAME,A.OSUSER,A.LOGON_TIME,A.LAST_CALL_ET/ 3600LAST_HOUR,A.STATUS, 'ORAKILL ' ||SID|| ' ' ||SPID HOST_COMMAND, 'ALTER SYSTEM KILL SESSION ''' ||A.SID|| ','||A.SERIAL#|| '''' SQL_COMMAND FROM V$SESSION A,V$PROCESS B WHERE A.PADDR=B.ADDR AND SID> 6 ;
查看排序段的性能 :
SQL >SELECT NAME , VALUE FROM V$SYSSTAT WHERE NAME IN ( 'SORTS (MEMORY)' , 'SORTS (DISK)' );
7 、查看数据库库对象 :
SELECT OWNER, OBJECT_TYPE, STATUS, COUNT (*) COUNT # FROM ALL_OBJECTS GROUP BY OWNER, OBJECT_TYPE, STATUS;
8 、查看数据库的版本 :
SELECT * FROM V$VERSION;
9 、查看数据库的创建日期和归档方式 :
SELECT CREATED, LOG_MODE, LOG_MODE FROM V$DATABASE;
10 、捕捉运行很久的 SQL:
COLUMN USERNAME FORMAT A12
COLUMN OPNAME FORMAT A16
COLUMN PROGRESS FORMAT A8
SELECT USERNAME,SID,OPNAME,ROUND(SOFAR* 100 / TOTALWORK, 0 ) || '%' AS PROGRESS,TIME_REMAINING,SQL_TEXT FROM V$SESSION_LONGOPS , V$SQL WHERE TIME_REMAINING <> 0 AND SQL_ADDRESS=ADDRESS AND SQL_HASH_VALUE = HASH_VALUE;
11 、查看数据表的参数信息 :
SELECT PARTITION_NAME, HIGH_VALUE, HIGH_VALUE_LENGTH, TABLESPACE_NAME,PCT_FREE, PCT_USED, INI_TRANS, MAX_TRANS, INITIAL_EXTENT,NEXT_EXTENT, MIN_EXTENT, MAX_EXTENT, PCT_INCREASE, FREELISTS ,FREELIST_GROUPS, LOGGING , BUFFER_POOL , NUM_ROWS, BLOCKS,EMPTY_BLOCKS, AVG_SPACE, CHAIN_CNT, AVG_ROW_LEN, SAMPLE_SIZE,LAST_ANALYZED FROM DBA_TAB_PARTITIONS
--WHERE TABLE_NAME = :TNAME AND TABLE_OWNER = :TOWNER
ORDER BY PARTITION_POSITION;
12 、查看还没提交的事务 :
SELECT * FROM V$LOCKED_OBJECT;
SELECT * FROM V$TRANSACTION;
13 、查找 object 为哪些进程所用 :
SELECT P.SPID,S.SID,S.SERIAL# SERIAL_NUM,S.USERNAME USER_NAME,
A.TYPE OBJECT_TYPE,S.OSUSER OS_USER_NAME,A.OWNER,A.OBJECT OBJECT_NAME,DECODE(SIGN( 48 - COMMAND),1 ,
TO_CHAR(COMMAND), 'ACTION CODE #' || TO_CHAR(COMMAND) ) ACTION,
P.PROGRAM ORACLE_PROCESS,S.TERMINAL TERMINAL,S.PROGRAM PROGRAM,S.STATUS SESSION_STATUS FROM V$SESSION S, V$ACCESS A, V$PROCESS P WHERE S.PADDR = P.ADDR AND S.TYPE = 'USER' AND A.SID = S.SID AND A.OBJECT = 'SUBSCRIBER_ATTR' ORDER BY S.USERNAME, S.OSUSER;
14 、查看回滚段 :
SQL >COL NAME FORMAT A10
SQL >SET LINESIZE 100
SQL >SELECT ROWNUM , SYS .DBA_ROLLBACK_SEGS.SEGMENT_NAME NAME , V$ROLLSTAT.EXTENTS EXTENTS , V$ROLLSTAT.RSSIZE SIZE_IN_BYTES, V$ROLLSTAT.XACTS XACTS, V$ROLLSTAT.GETS GETS, V$ROLLSTAT.WAITS WAITS, V$ROLLSTAT.WRITES WRITES, SYS .DBA_ROLLBACK_SEGS.STATUS STATUS FROM V$ROLLSTAT, SYS .DBA_ROLLBACK_SEGS, V$ROLLNAME WHERE V$ROLLNAME.NAME (+) = SYS .DBA_ROLLBACK_SEGS.SEGMENT_NAME AND V$ROLLSTAT.USN (+) = V$ROLLNAME.USN ORDER BY ROWNUM ;
15 、耗资源的进程 (top session):
SELECT S.SCHEMANAME SCHEMA_NAME,DECODE(SIGN( 48 - COMMAND), 1 , TO_CHAR(COMMAND), 'ACTION CODE #' || TO_CHAR(COMMAND) ) ACTION,STATUS SESSION_STATUS,S.OSUSER OS_USER_NAME,S.SID,P.SPID,S.SERIAL# SERIAL_NUM,NVL(S.USERNAME, '[ORACLE PROCESS]' ) USER_NAME,S.TERMINAL TERMINAL,S.PROGRAM PROGRAM,ST.VALUE CRITERIA_VALUE FROM V$SESSTAT ST,V$SESSION S,V$PROCESS P WHERE ST.SID = S.SID AND ST.STATISTIC# = TO_NUMBER( '38' ) AND ( 'ALL' = 'ALL' OR S.STATUS = 'ALL' ) AND P.ADDR=S.PADDR ORDER BY ST.VALUE DESC ,P.SPID ASC ,S.USERNAME ASC ,S.OSUSER ASC ;
根据 PID 查找相应的语句 :
SELECT A.USERNAME, A.MACHINE,A.PROGRAM,A.SID,A.SERIAL#,A.STATUS,C.PIECE,C.SQL_TEXT FROM V$SESSION A,V$PROCESS B,V$SQLTEXT C WHERE B.SPID=SPID AND B.ADDR=A.PADDR AND A.SQL_ADDRESS=C.ADDRESS(+) ORDER BY C.PIECE;
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根据 SID 找 ORACLE 的某个进程 :
SQL > SELECT PRO.SPID FROM V$SESSION SES,V$PROCESS PRO WHERE SES.SID= 21 AND SES.PADDR=PRO.ADDR; 监控当前数据库谁在运行什么 SQL 语句 : SQL >SELECT OSUSER, USERNAME, SQL_TEXT FROM V$SESSION A, V$SQLTEXT B WHERE A.SQL_ADDRESS =B.ADDRESS ORDER BY ADDRESS, PIECE; 如何查看数据库中某用户，正在运行什么 SQL 语句 SQL >SELECT SQL_TEXT FROM V$SQLTEXT T, V$SESSION S WHERE T.ADDRESS=S.SQL_ADDRESS AND T.HASH_VALUE=S.SQL_HASH_VALUE AND S.MACHINE= 'XXXXX' OR USERNAME= 'WACOS' ; 如何查出前台正在发出的 sql 语句 : SQL > SELECT USER_NAME,SQL_TEXT FROM V$OPEN_CURSOR WHERE SID IN (SELECT SID FROM (SELECT SID,SERIAL# FROM V$SESSION WHERE STATUS= 'ACTIVE' )); 查询当前所执行的 SQL 语句： SQL > SELECT PROGRAM ,SQL_ADDRESS FROM V$SESSION WHERE PADDR IN (SELECT ADDR FROM V$PROCESS WHERE SPID= 3556 ); PROGRAM SQL_ADDRESS ------------------------------------------------ ---------------- SQLPLUS@CTC20 (TNS V1-V3) 000000038 FCB1A90 SQL > SELECT SQL_TEXT FROM V$SQLAREA WHERE ADDRESS= '000000038FCB1A90' ; 找出消耗 CPU 最高的进程对应的 SQL 语句： SET LINE 240 SET VERIFY OFF COLUMN SID FORMAT 999 COLUMN PID FORMAT 999 COLUMN S_# FORMAT 999 COLUMN USERNAME FORMAT A9 HEADING "ORA USER" COLUMN PROGRAM FORMAT A29 COLUMN SQL FORMAT A60 COLUMN OSNAME FORMAT A9 HEADING "OS USER" SELECT P.PID PID,S.SID SID,P.SPID SPID,S.USERNAME USERNAME,S.OSUSER OSNAME,P.SERIAL# S_#,P.TERMINAL,P.PROGRAM PROGRAM,P.BACKGROUND,S.STATUS,RTRIM(SUBSTR(A.SQL_TEXT, 1 , 80 )) SQLFROM V$PROCESS P, V$SESSION S,V$SQLAREA A WHERE P.ADDR = S.PADDR AND S.SQL_ADDRESS = A.ADDRESS (+) AND P.SPID LIKE '%&1%' ; ENTER VALUE FOR 1 : PID¡ （这里输入占用 CPU 最高的进程对应的 PID ） SET TERMOUT OFF SPOOL MAXCPU.TXT SELECT '++' ||S.USERNAME USERNAME,RTRIM(REPLACE (A.SQL_TEXT,CHR( 10 ), '' ))|| ';' FROM V$PROCESS P, V$SESSION S,V$SQLAREA A WHERE P.ADDR = S.PADDR AND S.SQL_ADDRESS = A.ADDRESS (+) AND P.SPID LIKE '%&&1%' ; Enter value for 1: PID （这里输入占用 CPU 最高的进程对应的 PID ） spool off( 这句放在最后执行 ) CPU 用率最高的 2 条 SQL 语句的获取
SELECT SQL_TEXT FROM V$SQL WHERE ADDRESS IN (SELECT SQL_ADDRESS FROM V$SESSION WHERE SID IN (SELECT SID FROM V$SESSION WHERE PADDR IN (SELECT ADDR FROM V$PROCESS WHERE SPID=&PID))); |
SELECT A.TABLESPACE_NAME " 空间名称 ", 100 -ROUND((NVL(B.BYTES_FREE, 0 )/A.BYTES_ALLOC)* 100 , 2 ) " 占用率 (%) ", ROUND(A.BYTES_ALLOC/ 1024 / 1024 , 2 ) " 容量 (M) ",
ROUND(NVL(B.BYTES_FREE, 0 )/ 1024 / 1024 , 2 ) 空闲 (M) ",
ROUND((A.BYTES_ALLOC-NVL(B.BYTES_FREE, 0 ))/ 1024 / 1024 , 2 ) " 使用 (M) ",
LARGEST " 最大扩展段 (M) ",TO_CHAR(SYSDATE , 'YYYY-MM-DD HH24:MI:SS' ) " 采样时间 " FROM (SELECT F.TABLESPACE_NAME,SUM (F.BYTES) BYTES_ALLOC,SUM (DECODE(F.AUTOEXTENSIBLE, 'YES' ,F.MAXBYTES, 'NO',F.BYTES)) MAXBYTES FROM DBA_DATA_FILES F GROUP BY TABLESPACE_NAME) A,(SELECT F.TABLESPACE_NAME,SUM (F.BYTES) BYTES_FREE FROM DBA_FREE_SPACE F GROUP BY TABLESPACE_NAME) B,(SELECT ROUND(MAX (FF.LENGTH)* 16 / 1024 , 2 ) LARGEST,TS.NAME TABLESPACE_NAME FROM SYS .FET$ FF, SYS .FILE $ TF,SYS .TS$ TS WHERE TS.TS#=FF.TS# AND FF.FILE #=TF.RELFILE# AND TS.TS#=TF.TS# GROUP BY TS.NAME , TF.BLOCKS) C WHERE A.TABLESPACE_NAME = B.TABLESPACE_NAME AND A.TABLESPACE_NAME = C.TABLESPACE_NAME;
SELECT UPPER(F.TABLESPACE_NAME) " 表空间名 ",
D.TOT_GROOTTE_MB " 表空间大小 (M) ",
D.TOT_GROOTTE_MB - F.TOTAL_BYTES " 已使用空间 (M) ",
TO_CHAR(ROUND((D.TOT_GROOTTE_MB - F.TOTAL_BYTES) / D.TOT_GROOTTE_MB * 100 , 2 ), '990.99' ) " 使用比",F.TOTAL_BYTES " 空闲空间 (M) ",F.MAX_BYTES " 最大块 (M) " FROM (SELECT TABLESPACE_NAME,
ROUND(SUM (BYTES) / ( 1024 * 1024 ), 2 ) TOTAL_BYTES,
ROUND(MAX (BYTES) / ( 1024 * 1024 ), 2 ) MAX_BYTES
FROM SYS .DBA_FREE_SPACE
GROUP BY TABLESPACE_NAME) F,
(SELECT DD.TABLESPACE_NAME,
ROUND(SUM (DD.BYTES) / ( 1024 * 1024 ), 2 ) TOT_GROOTTE_MB
FROM SYS .DBA_DATA_FILES DD
GROUP BY DD.TABLESPACE_NAME) D
WHERE D.TABLESPACE_NAME = F.TABLESPACE_NAME
ORDER BY 4 DESC ;
24 、查询表空间的碎片程度 :
SQL >SELECT TABLESPACE_NAME,COUNT (TABLESPACE_NAME) FROM DBA_FREE_SPACE GROUP BY