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Oracle 最常用功能函数经典汇总

  * 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
     


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oracle数据类型number

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    NUMBER数据类型可以有两个限定符,如:
    column NUMBER ( precision, scale)
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ORACLE查询或删除时指定使用索引的写法­

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­
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ORACLE函数大全

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 ......
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