23.6 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 field(s) 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:

UTL_RAW.CAST_TO_RAW(DBMS_CRYPTO.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 23-6 MD5_CHECKSUM Parameters

Parameter	Description
p_value01 ... p_value50	Fifty available inputs. If no parameters are supplied, the default to NULL
p_col_sep	String used to separate p_value inputs. Defaults to the 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