Alert message from PLSQL in Oracle apex - oracle-apex-5.1

Question

I want to display an alert message from PLSQL if a certain condition is met. However it's not working.
Please check my PLSQL code which I wrote in dynamic action when clicking a checkbox.
declare
var_hire DATE ;
tenure_dt DATE;
i number;
TENURE EXCEPTION;
BEGIN
SELECT HIREDATE INTO var_hire from employee where empno=107;
-- APEX_APPLICATION.G_F01(1);
SELECT var_hire+ INTERVAL '1' YEAR INTO tenure_dt FROM DUAL;
IF SYSDATE < to_Date(tenure_dt,'DD-MON-YY') THEN
/* APEX_ERROR.ADD_ERROR (
p_message => 'The employee cannot be deleted',
p_display_location => apex_error.c_inline_in_notification );*/
apex_application.g_global_notification( 'The employee cannot be deleted');
END IF ;
END ;
declare
var_hire DATE ;
tenure_dt DATE;
i number;
TENURE EXCEPTION;
BEGIN
SELECT HIREDATE INTO var_hire from employee where empno=107;
-- APEX_APPLICATION.G_F01(1);
SELECT var_hire+ INTERVAL '1' YEAR INTO tenure_dt FROM DUAL;
APEX_ERROR.ADD_ERROR (
p_message => 'The employee cannot be deleted',
p_display_location => apex_error.c_inline_in_notification );
EXCEPTION
WHEN TENURE THEN
RAISE_APPLICATION_ERROR(-20000,'CANNOT BE DELETED');
END ;

Answer 1

You can create a Ajax callback process with your PL/SQL CODE. For example create the Ajax callback process as MyQuery
declare
var_hire DATE ;
tenure_dt DATE;
i number;
TENURE EXCEPTION;
BEGIN
SELECT HIREDATE INTO var_hire from employee where empno=107;
SELECT var_hire+ INTERVAL '1' YEAR INTO tenure_dt FROM DUAL;
IF SYSDATE < to_Date(tenure_dt,'DD-MON-YY') THEN
HTP.P('The employee cannot be deleted');
END IF ;
END ;
And then create a Dynamic Action ('Execute javascript Code) on your check box with below javascript code
apex.server.process('MyQuery', { },
{
dataType: "text",
success: function(pData) {
if (pData != "") {
apex.message.alert(pData);
}
}
});