MD5_CHECKSUM Function

Use this function for lost update detection. Lost update detection ensures data integrity in applications where data can be accessed concurrently.

This function produces hidden form fields with a name attribute equal to fcs and as value a MD5 checksum based on up to 50 inputs. APEX_ITEM.MD5_CHECKSUM also produces an MD5 checksum using Oracle Database DBMS_CRYPTO:

DBMS_CRYPTO.HASH(
    SRC => UTL_RAW.CAST_TO_RAW('my_string'),
    TYP => DBMS_CRYPTO.HASH_MD5 );

An MD5 checksum provides data integrity through hashing and sequencing to ensure that data is not altered or stolen as it is transmitted over a network.

Syntax

APEX_ITEM.MD5_CHECKSUM(
    p_value01   IN    VARCHAR2 DEFAULT NULL,
    p_value02   IN    VARCHAR2 DEFAULT NULL,
    p_value03   IN    VARCHAR2 DEFAULT NULL,
    ...
    p_value50   IN    VARCHAR2 DEFAULT NULL,
    p_col_sep   IN    VARCHAR2 DEFAULT '|',
    p_item_id   IN    VARCHAR2 DEFAULT NULL)
    RETURN VARCHAR2;

Parameters

Table 27-6 MD5_CHECKSUM Parameters

Parameter Description

Parameter	Description
`p_value01` `...` `p_value50`	Fifty available inputs. If no parameters are supplied, defaults to NULL.
`p_col_sep`	String used to separate `p_value` inputs. Defaults to \| (pipe symbol).
`p_item_id`	ID of the HTML form item.

p_value01

...

p_value50

Fifty available inputs. If no parameters are supplied, defaults to NULL.

p_col_sep String used to separate p_value inputs. Defaults to | (pipe symbol).

p_item_id ID of the HTML form item.

Example

This function generates hidden form elements with the name fcs. The values can subsequently be accessed by using the APEX_APPLICATION.G_FCS array.

SELECT APEX_ITEM.MD5_CHECKSUM(ename,job,sal) md5_cks,
       ename, job, sal
FROM emp