GET_HASH Function

This function computes a hash value for all given values. Use this function to implement lost update detection for data records.

Syntax

APEX_UTIL.GET_HASH (
    p_values IN apex_t_varchar2,
    p_salted IN BOOLEAN DEFAULT TRUE )
    RETURN VARCHAR2;

Parameters

Parameter	Description
`p_values`	The input values.
`p_salted`	If TRUE (default), salt hash with internal session information.

Example

This example updates the SAL and COMM columns of a given record in the EMP table, but throws an error if the column data has changed in the meantime.

declare
       l_hash varchar2(4000);
   begin
       select apex_util.get_hash(apex_t_varchar2 (
                  empno, sal, comm ))
         into l_hash
         from emp
        where empno = :P1_EMPNO;
 
       if :P1_HASH <> l_hash then
           raise_application_error(-20001, 'Somebody already updated SAL/COMM');
       end if;
 
       update emp
          set sal = :P1_SAL,
              comm = :P1_COMM
        where empno = :P1_EMPNO;
   exception when no_data_found then
       raise_application_error(-20001, 'Employee not found');
   end;