DUMP

Syntax

Description of the illustration dump.eps

Purpose

DUMP returns a VARCHAR2 value containing the data type code, length in bytes, and internal representation of expr. The returned result is always in the database character set. For the data type corresponding to each code, see Table 2-1.

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 each byte printed as a character if and only if it can be interpreted as a printable character in the character set of the compiler—typically ASCII or EBCDIC. Some ASCII control characters may be printed in the form ^X as well. Otherwise the character is printed in hexadecimal notation. All NLS parameters are ignored. Do not depend on any particular output format for DUMP with return_fmt 17.

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

This function does not support CLOB data directly. However, CLOBs can be passed in as arguments through implicit data conversion.

See Also:

• Data Type Comparison Rules for more information

• Appendix C in Oracle Database Globalization Support Guide for the collation derivation rules, which define the collation assigned to the character return value of DUMP

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'
  ORDER BY employee_id;

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

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

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