Oracle Form Global Variable Recognition
In the name of
Allah, Most Gracious, Most Merciful
Praise be to
Allah, blessing and peace be upon our prophet Mohammed, his family and his companions.
After that,
Global Variable
·
Global variables has a global scope; it is visible (accessible) throughout your
application program.
·
Global variables are used extensively to pass information
between forms.
·
Global variables can be initialized or declared in two different ways:
- DEFAULT_VALUE built-in. DEFAULT_VALUE ('Al-Emran', 'global.company_name');
- PL/SQL assignment statement Global.company_name := 'Al-Emran';
Global Variable Types
Oracle Forms Developer and PL/SQL
support different types
- Oracle
Forms Global: a variable in the "global" pseudo-block of a form
- PL/SQL
Package Global: a global defined in the specification of a package
- Oracle
Forms Parameter: a variable created within the Oracle Forms Designer as a
Parameter
Pls. see the Oracle Forms
Reference Manual for a complete
description of these variable types.
The following table lists the characteristics
of each type of variable, and enables you to select the type most appropriate
for your code.
Behavior
|
Oracle Forms Global
|
PL/SQL Package
Global
|
Oracle Forms
Parameter
|
Can be created at
Design time
|
Y
|
Y
|
|
Can be created at
runtime
|
Y
|
||
Accessible across all
forms
|
Y
|
||
Accessible from
attached libraries
|
Y
|
(1)
|
Y
|
Support specific data
types
|
(2)
|
Y
|
Y
|
Have declarative
defaults
|
Y
|
||
Can be referenced
indirectly
|
Y
|
Y
|
|
Can be specified on
command line
|
Y
|
||
Must be erased to
recover memory
|
Y
|
||
Can be used in any
Oracle Forms code
|
Y
|
Y
|
Global Variable Limitations
·
Global variables do not generate any compilation errors during development stage but only
run-time errors.
·
Global variables are always characters. If you are not familiar with this fact, your expected output
will not work; no effect.
Now Current situation
§ On
development stage,
at design-time, you will not face any compilation error.
§ On test stage, at run-time you will not
face any run-time error.
You will have just silent failure with no explanation and sucked helpless. It's better to know this case before wasting effort and time.
· A significant drawback
of Global variables;
it consumes high memory resources:
§ Memory is an
important resource for your application so it’s wise to consider choosing other
alternatives for Global variables.
§ Form Parameters are recommended alternative
instead of using Global variables.
· Global variables usage is recommended Not
to use them if un-necessary.
· Global variables persist in memory until you remove it
externally with the ERASE () built-in procedure.
· Global variables must be declared, if Not
initialize before execution, it will generate run-time error.
FRM-40815 GLOBAL. does not exist.
Warning Avoid above error by assigning the
appropriate value to the global variable before opening the
new form.
·
In fact, they are usually considered bad practice
precisely because of their non-locality.
· Each Global
variable Must has the same name to each form session.
Warning:
Oracle
recommends explicit conversions, rather than rely on implicit or automatic conversions for
these reasons:
·
You will need using a NUMBER using the TO_NUMBER() function
or using TO_DATE() functions.
For more related
detailed Global variables usage pls read
Hope this helps…
My success only comes from Allah, pls.
note your comments and suggestions are great help for me in progress thanks in
advance.
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