| ect 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
Oracle 最常用功能函数经典汇总
来源：ChinaITLab 收集整理
2004-6-14 10:58:00
* SQL Group Function
*
s (num can be a column or ex
pression)
(null values are ign
*
ored, default between distin
ct and all is all)
********************
***************
****************************
****************
AVG([distinct or all] num)
-- average value
COUNT(distinct or all] num)
-- number of values
MAX([distinct or all
] num) -- maximum value
MAX([distinct or all] num)
-- minimum value
STDDEV([distinct or
all] num) -- standard devi
ation
SUM([distinct or all
] num) -- sum of values
VARIANCE([distinct o
r all] num) -- variance of v
alues
********************************
***********************
************************
* Miscellaneaous Functions :
*
********************
***************
****************************
****************
DECODE(expr, srch1,
return1 [,srch2, return2...]
, default]
-- if no search matches t
he expression then the default is returned,
-- otherwise,
the first search that match
es will cause
-- the corres
ponding return value to be r
eturned
DUMP(column_name [,fmt [,start_p
os [, length]]])
-- returns an
column
internal oracle format, used
for getting info about a
-- format options : 8 = oc
tal, 10 = decimel, 16 = hex, 17 = characters
-- return type
codes : 1 = varchar2, 2 = n
umber, 8 = long, 12 = date,
-- 23 = raw,
24 = long raw, 69 = rowid,
96 = char, 106 = mlslabel
GREATEST(expr [,expr2 [, expr3...]]
-- returns the largest val
ue of all expressions
LEAST(expr [,expr2 [, expr3...]]
-- returns the
smallest value of all expre
ssions
NVL(expr1 ,expr2
-- if expr1 is not null, i
t is returned, otherwise expr2 is returned
SQLCODE
-- returns sql error code
query,
of last error. Can not be used directly in
-- value must
be set to local variable fir
st
SQLERRM
-- returns sql
in query,
error message of last error
. Can not be used directly
-- value must be set to lo
cal variable first
UID
-- returns the user id of
the user you are logged on as
-- useful in s
electing information from lo
w level sys tables
USER
-- returns the
user name of the user you a
re logged on as
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