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How to use Oracle Dump Function

作者：eygle |【转载时请以超链接形式标明文章出处和作者信息及本声明】
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DUMP returns a VARCHAR2 value containing the datatype code, length in bytes, and internal representation of expr. The returned result is always in the database character set.

The syntax is:

DUMP(expr[,return_fmt[,start_position[,length]]])

The argument return_fmt specifies the format of the return value and can have any of the following values:

• 8 returns result in octal notation.
• 10 returns result in decimal notation.
• 16 returns result in hexadecimal notation.
• 17 returns result as single characters.

By default, the return value contains no character set information. To retrieve the character set name of expr, specify any of the preceding format values, plus 1000. For example, a return_fmt of 1008 returns the result in octal, plus provides the character set name of expr.

The arguments start_position and length combine to determine which portion of the internal representation to return. The default is to return the entire internal representation in decimal notation.

If expr is null, then this function returns a null.

Examples

The following examples show how to extract dump information from a string expression and a column:

SELECT DUMP('abc', 1016)
   FROM DUAL;

DUMP('ABC',1016)
------------------------------------------
Typ=96 Len=3 CharacterSet=WE8DEC: 61,62,63

SELECT DUMP(last_name, 8, 3, 2) "OCTAL"
   FROM employees
   WHERE last_name = 'Hunold';

OCTAL
-------------------------------------------------------------------
Typ=1 Len=6: 156,157

SELECT DUMP(last_name, 10, 3, 2) "ASCII"
   FROM employees
   WHERE last_name = 'Hunold';

ASCII
--------------------------------------------------------------------
Typ=1 Len=6: 110,111

By eygle on 2005-11-10 12:33 | Comments (0) | Posted to HowTo | SQL.PLSQL | Edit |

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