SQL内置函数的使用方法及结果(9)

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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

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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

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GAO 25