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Question 1: What is Form Builder?
Form builder is a component of Oracle Developer that is used to develop form based Applications for presenting and manipulating data.
Question 2: What is a difference between Frame, Item and Block?
Frame is used to arrange data block items. Item are Members of data block. Items grouped into Records. Block provides a mechanism for grouping related items into a functional unit for storing, displaying and manipulating Records.
Question 3: What is a difference between Window, Canvas and View Port?
Window is a container for all visual objects that make up a form application. Window performs functionality such as scrolling, moving and resizing. A single form may include several windows. Each window should have at least one content canvas. Each new form module has one predefined window which is called Window1 and is a modeless window.
Canvas is a surface inside a window on which visual objects can be placed. A canvas is assigned to a window. Each item in a form must refer to not more than one canvas.
View port is a visible portion of canvas.
Question 4: What is MDI?
MDI (Multiple Document Interface) is a parent window through which multiple documents can be accessed and browsed.
Question 5: What is a difference between Modal and Modeless window?
Modal Window is a restricted window that requires a window exit before moving to another window. You cannot move freely between windows. Modeless Window is an unrestricted window that the user can move freely. User can have simultaneously access to more than one window.
Question 6: What are Canvases in Oracle Forms and describe different types of Canvases?
Canvas is a surface inside a window on which visual objects can be placed. A canvas is assigned to a window. Each item in a form must refer to not more than one canvas.
Types of Canvases:
1) Content Canvas
2) Stacked Canvas
3) Toolbar Canvas
a) Vertical Toolbar
b) Horizontal toolbar
4) Tab Canvas
Content Canvas is a base canvas and is a default canvas type. Content canvas occupies the entire content area of the window. More than one content canvas can be assigned to the same window but only one content canvas can be displayed on a window at a time. To display more than one content canvas at the same time, assign each content canvas to a different window.
Stacked Canvas is displayed on top of the content canvas and is usually small in size then that of content canvas in the same window. To convert an existing content canvas to a stacked canvas, simply change its canvas type property from content to stack. To show and hide canvases programmatically, use the SHOW_VIEW, HIDE_VIEW and SET_VIEW_PROPERTY built-ins. stacked canvas is useful to display additional information, for hiding information and can act as a scrolling view.
Toolbar Canvas is used to create toolbar for individual window. Toolbar canvas is of two types: Vertical and Horizontal toolbar canvases.
Vertical Toolbar canvas is displayed to the left of a content canvas. Horizontal Toolbar canvas is displayed at the top of a content canvas. Toolbar canvas is used to hold buttons and other frequently used GUI elements. Toolbar canvas increases application usability and decrease form module maintenance Time. Object Navigator window has both horizontal and vertical toolbars where as Property Palette has a horizontal toolbar only. You can also create more than one toolbar for the same window. MDI Toolbar: Attaching a Toolbar to a form provides a MDI toolbar, so that there is no need to create more than one toolbar for a form application that uses multiple windows. Toolbar can be attached to individual windows or to the form itself.
Tab Canvas enables the user to organize and display data on separate Tabs. Tab canvas is displayed on top of the Content Canvas. Each Tab canvas is made up of one or more Tab pages and must have at least one. Each Tab page occupies an equal amount of space on Tab canvas. Any Item you place on a Tab canvas has a Canvas property as well as Tab page Property. The ordering of Tab pages in the object navigator determines the left-to-right or Top-To-bottom order of the Tabs at runtime. Tab canvas provides easy access to data and displays large amount of data on a single canvas and is also used to hide information.
Question 7: What are Messages and Alerts?
Messages and Alerts are the form of communication between the application and the User.
Types of Messages:
1) Informative message
2) Error message
3) Working message
4) Application message
Informative Message informs the user about the current state of processing. Example: Last value retrieved Press [Accept] to enter answer. Informative messages can be suppressed with an On-Message Trigger.
Error Message informs the user about the errors interrupting the processing. Example: Function key not allowed. Press [Show function keys] for list of valid keys too many arguments on command line. Error messages can be suppressed with an On-Error Trigger.
Working Message informs the operator that the form is currently in processing. Example: Working… Working message can be suppressed by setting the system variable SUPPRESS_WORKING to True.Example: Sytem.suppress_working: =’TRUE’
Application Message is created by the programmer using the MESSAGE built-in.
Types of Alerts:
1) System Alert
2) Application Alert
Alerts are displayed in a Modal window.
System Alert is a system acknowledgement to the operator before processing can be continue.
Application Alert are designed and created by the programmer as part of application using SHOW_ALERT built-in.
Question 8: Explain Message Severity level in Oracle Forms?
Message Severity Level is used to suppress messages according to the severity level. There are six different severity levels that the programmer can affect: 0, 5, 10, 15, 20, and 25. The default value is 0 for all messages. If the severity level is greater than 25 than the Message cannot be suppressed. During a run form session, form builder suppresses all messages with severity levels that are the same or lower than the indicated severity level. Defined with: system.message_level. Form builder does not suppress prompts or vital error messages, no matter what severity level you select.
Question 9: When can the Triggers in oracle forms can be failed?
Triggers are failed only when one of the following occurs:
a) During an Unhandled exception
b) By raising built-in exception FORM_TRIGGER_FAILURE. Means failing a trigger in a controlled manner.
c) FORM_TRIGGER_FAILURE is a predefined Pl/Sql exception available only in form Builder.
Question 10: What is a difference between ON-ERROR and ON-MESSAGE Trigger?
ON-ERROR Trigger fires whenever an Oracle Forms causes an error message to display. ON-ERROR Trigger is used to replace default error message with a customized Message. Built-in functions that are used to determine the Error message are: ERROR_CODE, ERROR_TEXT, ERROR_TYPE (FRM, ORA).
ON-MESSAGE Trigger fires whenever an Oracle Forms causes a message to display. ON-MESSAGE Trigger is used to replace default message with a customized Message. Built-in functions that are used to determine the message are: MESSAGE_CODE, MESSAGE_TEXT, MESSAGE_TYPE (FRM, ORA, NULL).
Question 11: Name the types of Alert properties?
Types of Alert properties are: Stop, Caution and Note.
Question 12: What are Input items? Explain different types of Input items?
Input Items are those items that accepts user Input. Input items enables insert, update, delete or query an item process.
Types of Input Items:
Check Box is a two-state interface object that indicates whether a certain value is Checked or unchecked. Trigger associated with check box is WHEN-CKECKBOX-CHANGED.
WHEN-CHECKBOX-CHANGED:This Trigger fires whenever an operator changes the state of a check box, either by clicking with the mouse or through keyboard interaction.
List Item consists of many alternative choices, out of which one and only one can be selected at a time. There are three types of list item: Poplist, Tlist and Combo Box. Poplist is a field with an iconic button attached to the right side. When user clicks on a poplist, all of its elements are displayed. Tlist appears as a rectangular box that displays the list elements. Scroll bar appears to the right side of the list, if the list is bigger.
Combo box accepts user input. Appears as a field with a down arrow next to its right side. Trigger associated with list item is WHEN-LIST-CHANGED. WHEN-LIST-CHANGED Trigger fires when an operator selects a different element in a list item or de-selects the currently selected element. In addition, if a When-List-Changed trigger is attached to a combo box style, it fires each time the operator enters or modifies the entered text.
Radio Group consists of a fixed number of radio button options and only one can be selected at a time. It is alternative to List item. Consider List Item instead of Radio Group if there are more than four or five choices. Trigger associated with Radio Group is WHEN-RADIO-CHANGED. WHEN-RADIO-CHANGED Trigger fires when an operator selects a different Radio button in a radio group or de-selects the currently selected radio button either by clicking with the mouse or through keyboard interactions.
Question 13: What are Non-Input items? Explain its types?
Non-Input Items are those items that do not accept direct user input.
Types of Non-Input items:
Display Item is a read-only text item. Display item is similar to text item except that it cannot not be edited, queried, Navigated or accepts user input.
Image Item is used to store and display images. User can populate an image item either by fetching from a LONG RAW or BLOB Column or by using a trigger and a built-in to populate the image item programmatically. Images can be stored in either the database or the file system. When user insert images into the database by means of a save (commit), they are automatically compressed using the Oracle image compression. Images can also be populated with a BFILE, but will need to use DBMS_LOB to do so. Images cannot be cached. Triggers associated with the image item are: WHEN-IMAGE-ACTIVATED, WHEN-IMAGE-PRESSED. WHEN-IMAGE-ACTIVATED Trigger fires whenever an operator selects or de-selects the image item. WHEN-IMAGE-PRESSED Trigger fires whenever an operator single-click or double-click on an image item.
Push Button Push Button is a non-input item that does not store or display data. Push Button is an interface object that is clicked to initiate an action. It is used for: Navigating between items, Display an LOV, Invoke an editor, calling to another window, Commit the data, Issue a query, Perform Calculations. Trigger associated with the Push Button is: WHEN –BUTTON-PRESSED.WHEN-BUTTON-PRESSED Trigger fires when an operator selects a button either by way of key or by clicking with a mouse.
Calculated Items are read-only items that are used for performing calculations. Can be expressed as: Formula Calculated Item: Performs horizontal calculations. Involves bind variables. Summary calculated Item: Performs Vertical calculations on values of a single item over all rows in a block.
Hierarchical Tree Items displays data in the form of standard Navigator style.
Bean Area Item enables you to integrate JAVA components into your application.
JAVA Bean is a component written in JAVA that can plug into any applet or JAVA application. JAVA Beans helps to interact with the client machine.
Question 14: What are Relations in Oracle Forms and explain its types?
Relations involve the Master-Detail relationship. Relation can be build automatically through Data block wizard or manually through create toolbar.
Types of Relations:
Non-Isolated Relation is a default Type. Prevent the deletion of master record if the associated child record exists in the database. Default Triggers type that are created by this relation are: ON-CLEAR-DETAILS (Form-level), ON-POPULATE-DETAILS (Block-level), ON-CHECK-DELETE-MASTER (Block-level).
Isolated Relation allows the master record deletion if the associated child record exists. Default Triggers type that are created by this relation are: ON-CLEAR-DETAILS (Form-level), ON-POPULATE-DETAILS (Block-level).
Cascading Relation allows the deletion of child record if the associated master record is deleted. Default Triggers type that are created by this relation are: ON-CLEAR-DETAILS (Form-level), ON-POPULATE-DETAILS (Block-level), PRE-DELETE (Block-level).
The default program units (procedures) created for above all three types of Relations are the same: CHECK_PACKAGE_FAILURE, CLEAR_ALL_MASTER_DETAILS, and QUERY_MASTER_DETAILS.
Question 15: What is Co-ordination Causing Event? Explain different types of Co-ordination?
Any event that changes the current record in a Master block is a Co-ordination Causing Event.
Types of Co-ordination:
2) Automatic Query
Three Conditions for coordination causing event are:
1) Immediate (Deferred=NO, Automatic Query=NO)
2) Deferred (Deferred=YES, Automatic Query=NO)
3) Deferred with Automatic Query (Deferred=YES, Automatic Query=YES)
Immediate: When the coordination-causing event occurs, Form builder fetches the detail record immediately.
Deferred: When the coordination-causing event occurs, the Form Builder has to navigate to the detail Block and executes the query in order to fetch the detail records.
Deferred with Automatic Query:
When the coordination-causing event occurs, the Form Builder has to navigate to the Detail Block in order to fetch the detail records.
Question 16: What are the two phases of block coordination?
Two phases of block coordination are:
Clear Phase: During the clear phase Oracle forms navigates internally to the detail block and fetches the detail records.
Population Phase: During a population phase Oracle forms issue a select statement to repopulate the detail records associated with the new master record.
Question 17: What are Editors? Explain different types of editors in oracle forms?
Editors are used for special requirements such as: larger editing window, Search/Replace, cut, copy, paste etc.
Types of Editors:
1) Default Editor
2) System Editor
3) User-Named Editor
Default Editor: The default editor provides standard editing features, including search/replace and cut, copy, and paste. The default editor is built into every form and is automatically available from every text item.
System Editor: If there is a system editor available, you can specify that Form Builder should use the current system editor, rather than the default editor.
User-Named Editor: Is a named object. You can specify editor attributes such as Window display size, Position and Title.
Built-in used for Editor:
SHOW-EDITOR: Is a built-in procedure, which accepts any editor name and takes some I/P string and returns modified O/P string.
EDIT_TEXTITEM: Needs the input focus to be in the text item before the built-in is executed.
Question 18: What is a LOV? Explain its types?
LOV (List of Values): An LOV is a scrollable popup window with either single or multi-column selection list.
Types of LOV:
Static LOV: Contains the predetermined values.
Dynamic LOV: Contains values that come at runtime.
LOV for Validation property of an item:
When LOV for validation is set to true, Oracle forms compares the current value of the Text item to the values in the first column displayed in the LOV whenever the Validation event occurs. If the value in the text item matches one of the values in the first column of LOV, validation succeeds, the LOV is not displayed and the processing continues normally. If the value in the text item does not match one of the values in the first column of the LOV, Oracle forms displays the LOV and uses the Text item value as the search criteria to automatically reduce the list.
Built-in used to display the LOV are: SHOW_LOV (Function), LIST_VALUES (Procedure). Built-in that is used for setting the LOV properties: SET_LOV_PROPERTY, GET_LOV_PROPERTY.
Question 19: What are Property Classes?
A Property Class is a named object that contains a list of properties and their settings. There can be any number of properties in a property class and the properties in a class can apply to different types of objects. Property Class can be subclass in any number of modules. Property Class can have Triggers. You can define a Trigger in a property class when you want a form, block or item that you base on the class to inherit the trigger. When you define a trigger in a property class, the trigger appears in the object navigator under the trigger node for the class, but does not appear under the trigger node for objects based on the class.
Question 20: What are the various different types of Properties in Oracle Forms?
The various different types of Properties in Oracle Forms are:
Default Property: Is the default property of an object. Is denoted by a circle.
Changed Property: When changing the default property value of an object to some new value. Is denoted by a square.
Inherited Property: Is one that takes its value from the property class. It is displayed with an arrow to the left of the property name.
Variant Property: Changes a value of inherited property results to a variant property. It is displayed with a red cross over an arrow.
Question 21: What are Visual Attributes?
Visual Attributes are the font, color and pattern properties that can be set for form and Menu objects. Visual Attributes includes the Font Properties such as Font name, font size, font style Font width etc. and color or pattern properties such as foreground color, background Color, Fill pattern etc.
Question 22: What is an Object Group?
Object Group is used to package related Form Builder objects so that they can be copied or used in another module. Example: You might build a appointment scheduler in a form and then decide to make it available from other forms in your applications. The scheduler would probably be built from several types of objects, including a window, canvas, blocks and items that display dates and appointments and, Triggers that contain the logic for scheduling and other functionality. If you packaged these objects into an object group, you could then copy them to any number of other forms in one simple operation. You can create object groups in form and menu modules. Once you create an object group, you can add and remove objects to it as desired. Dragging a block into an object group implicitly includes all objects that are contained within that block. (Items, triggers, relations etc.). The objects in a group must all be defined in the same module, you cannot place objects from two different forms in the same object group. An object group cannot contain another object group. When an object in an object group is deleted from a module, it is removed from the object group automatically. Deleting an object group from a module does not delete the objects it contains from the module.
Question 23: What is a Record Group?
Record Group defines the data structure that is used to represent LOV and also used to exchange data between forms. A record group can have an unlimited number of columns of type CHAR, NUMBER, or DATE provided that the total number of columns does not exceed 64K. Record Group column names cannot exceed 30 characters. Record Group is local to Form Builder, rather than existing in the Database.
Question 24: Explain different types of Record Groups?
Different types of Record Groups are:
Query Record Group has an associated Select statement and is derived from the Database table.
Non-Query Record Group does not associate with the Query and its structure and values can be modified programmatically at runtime. Non-Query Record Group can be created and modified only at runtime.
Static Record Group does not associated with Query, instead can define its structure and row values at design time and they remain fixed at runtime. Static Record Group can be created and modified only at design time.
Question 25: What is a difference between Object and PL/SQL Libraries?
Object Libraries are the collection of Form objects that can be used in other modules. Can contain simple objects, property classes, object groups and program units.
PL/SQL Libraries are the collection of PL/SQL Program units including procedures, Functions and packages whose code can be referenced and called from other modules.
Question 26: What are Smart Classes?
Smart Class is an object in an object library that is frequently used as a class.
Question 27: What is OC4J?
OC4J stands for Oracle Containers for J2EE. OC4J is preferred to run form applications. Oracle connectivity with JAVA is done through OC4J. On NT, run Batch file to start (startinst.bat) or stop (stopinst.bat) OC4J. OC4J starts in DOS Window. Minimize the window in order to work; closing the window will abort OC4J.
Question 28: What is a Console?
Console provides information at Runtime. Console consists of: Message line and Status line. Message Line: The Message line displays both form and application messages. Status Line: The Status Line displays a variety of Indicators to reflect the current status of the Form Module. Such as: Record n/m, enter-query, List of values etc.
Question 29: What is a difference between OPEN_FORM, CALL_FORM and NEW_FORM?
OPEN_FORM: OPEN_FORM opens another form in a modeless window. The user can work on multiple forms concurrently. The user can navigate within multiple forms. With the OPEN_FORM the user can call another form in a different database session. Syntax: OPEN_FORM (‘form_name’, active_mode, session_mode, data_mode, paramlist); default: activate and no session mode. OPEN_FORM is a restricted procedure and cannot be called in the Enter-Query mode.
CALL_FORM: CALL_FORM calls another form in a Modal window. The user cannot navigate within different Forms. Requires to exit the called form before navigating back to the calling form. Forms are called in the same session.
NEW_FORM: NEW_FORM exits the current form and opens the new form as a parent window. NEW_FORM releases the memory by exiting the current form.
Question 30: What are the benefits of multiple form Applications?
Benefits of Multiple form Applications are:
- Easier to debug small form.
- Flexibility between forms.
- Easy to maintain.
- Data can be exchanged between forms.
Question 31: Explain different methods for exchanging data between forms?
Data can be exchanged between forms by four different means:
1) Through Global variables
2) Through Parameter Lists
3) Through Global Record Groups
4) Through PL/SQL variables in shared libraries.
Through Global Variables: Global variables contain character data values with a maximum of 255 characters. Each Global variable is known by the same name to each form in the session. Can be created by a PL/SQL assignment, or by the DEFAULT_VALUE built-in. Example :GLOBAL.cust.id, DEFAULT_VALUE (‘’,’GLOBAL.cust_id). If the Global variable has not been initialized before it is referenced in a called form an error is reported.In order to ensure the existence of global variable use the DEFAULT_VALUE built-in. To remove default_value built-in use ERASE built-in. Ex: ERASE (‘global_name’).
Through Parameter Lists: Parameter can be of any data type. The use of parameters in Multi-form applications is limited by the fact that they are visible only to the form in which they are defined. The built-in OPEN_FORM optionally takes as an argument the name or id of a parameter list. The Built-ins that enable the user to work with parameter lists includes: GET_PARAMETER_LIST, CREATE_PARAMETER_LIST, DESTROY_PARAMETER_LIST, ADD_PARAMETER, DELETE_PARAMETER. Example: Parameter.cust_id.
Through Global Record Groups: To use Global Record Group:-
1) Use CREATE_GROUP_FROM_QUERY to create the record group with Global_scope.
2) Populate the Record Group with the POPULATE_GROUP built-in.
3) The Record Group is now available to any form in the same session.
Through PL/SQL Variable in Shared Libraries: PL/SQL Variable use less memory than Global Variables. PL/SQL Variable can be of any Data Type.
To use PL/SQL variables:
1) Create a PL/SQL Library.
2) Create a package specification with variables.
3) Attach the library to multiple forms.
4) Set Variable values in calling form.
5) OPEN_FORM with SHARE_LIBRARY_DATA option.
6) Use variables in opened form.
Example: OPEN_FORM (‘called_lib’, Activate, No_session, Share_library_data)
Question 32: Explain EXIT_FORM in Oracle Forms?
EXIT_FORM Built-in is used for closing or exiting the form.
Syntax: EXIT_FORM (ASK_COMMIT or DO_COMMIT or NO_COMMIT or NO_VALIDATE)
ASK_COMMIT: IS a default type. Gives the decision to the user.
DO_COMMIT: Posts and commit changes across all form for the current transaction.
NO_COMMIT: Validates and rollback uncommitted changes in the current form.
NO_VALIDATE: Is the same as NO_COMMIT but without validation.
Question 33: How code between forms can be shared?
Codes between forms can be shared through the followings:
1) Library Modules by attaching them to each form as required.
2) Stored Program Units in the database.
Question 34: Explain SYNCHRONIZE Built-in?
SYNCHRONIZE built-in is used to synchronize the Terminal Screen with the internal State of the form. SYNCHRONIZE update the screen display to reflect the information that Form Builder has its internal representation of the screen.
FOR J IN 1..1000 LOOP
Question 35: What is a difference between Data and Control Block?
DATA BLOCK: Data Block is directly associated with the Database. This enables the user to automatically access and manipulates data in the database. Data Block is associated with either a Database Table (or View), a stored procedure, A From clause query, or Transactional triggers. Items in the data block are called data items or base table items.
CONTROL BLOCK: Control Block is created manually, they are not associated with the Database. Items in the Control Block are called Control items.
Question 36: What is a Debugger?
With the Debugger you can monitor the execution of code within the trigger and other program units. The steps include:
1) Step Into: Executes the next statement.
2) Step Over: Executes the next statement without stepping into a nested subprogram.
3) Step Out: completes the nested subprogram and steps to the next executable statement in the calling program.
4) Go: resumes execution until the program terminates normally or is interrupted by the next breakpoint.
5) Pause: Pauses the execution of running PL/SQL code to enable you to examine the environment. For Example, you could check variable values.
6) Stop: Terminates debugging and program execution completely.
Question 37: What is an Indirect Reference?
Items can be referenced indirectly with the NAME_IN and COPY built-in Subprograms. Use Indirect referencing when you create procedures and functions in a library Module, because direct references cannot be resolved.
Question 38: What is a difference between NAME-IN and COPY built-in?
NAME-IN built-in (function): Returns the value of the indicated variable. The returned value is in the form of a character string. Use conversion functions for Number and Date. The NAME_IN function cannot return the contents of a global or local variable. In PL/SQL triggers that will be executed in enter_query mode, you must use NAME_IN rather than normal bind-variable notation to access values in the data-block. Bind variables cannot be referenced directly in the PL/SQL statements.
IF :emp.ename=’abc’—-Direct Reference
IF NAME_IN(‘emp.ename’)=’abc’—-Indirect Reference
COPY built-in (Procedure): The COPY built-in assigns an indicated value to an indicated variable or item. The COPY built-in is used for copying a value from one item or variable into another item or global variable. Use COPY built-in because you cannot use standard PL/SQL syntax to set a referenced item equal to a value.
Question 39: What is allowed and not allowed in Enter-Query Mode?
Enter-Query Mode Allows:
1) Retrieve all Records
2) Retrieve records by using selection criteria.
Enter-Query Mode does not Allows:
1) Navigate out of the current block
2) Exit from the runtime session
3) Use certain functions such as Next Record.
4) Insert new records
5) Updating existing records
6) Deleting Records.
Question 40: What is a Menu Module in Oracle Forms?
Menu Module consists of a hierarchy of menus, each with selectable items.
Question 41: Explain ONETIME_WHERE property?
For instances where you want to restrict the query only once, you can programmatically set the ONETIME_WHERE property of a block.
Question 42: What are the different methods of Navigation in Oracle Forms?
Different methods of Navigation are:
1) Default Menu
2) Menu Toolbar
5) Function Keys
Question 43: What is a sequence of firing Triggers at Form level in Oracle Forms?
Sequences of firing Triggers at form level:
Question 44: What is a sequence of firing Triggers at Item level in Oracle Forms?
Sequence of firing Triggers at Item level:
Question 45: What are the different types of Form builder variables?
Different types of Form builder variables are:
1) Item (:block_name.item_name)
2) Global (:GLOBAL.variable_name)
3) System (:SYSTEM.variable_name)
4) Parameter (:PARAMETER.name).
Question 46: What are the standard validation checks for Text item?
Standard validation checks for Text Item are:
1) Format mask
3) Data Type
4) Lowest-Highest allowed Value
5) Validate from List
Question 47: Explain Defer Requirement Enforcement?
This property applies only when item-level validation is in effect. When DRE is set to Yes than WHEN-ITEM-VALIDATION Trigger does not fire. That is Item Level validation does not take place, then the error will be tracked during record-level validation.
Question 48: Explain the benefits of reusing objects and code in Oracle Forms?
Benefits of reusing objects and code are:
1) Increase Productivity: Reusing objects and code decreases development time, thereby increasing productivity.
2) Decrease Maintenance: Changing the code at one place reflects at many other places, thereby reducing maintenance time.
3) Increase modularity: Sharing and reusing code increases the modularity of the applications.
4) Maintain Standards: Standard objects and code can be used for multiple form modules.
5) Improved Application Performance: By decreasing Network Traffic.
Question 49: Explain Triggers in Oracle Forms? Also explain different categories of Triggers?
Triggers are blocks of PL/SQL code that is written to perform some specific tasks. Trigger is a program unit that is executed or fired due to an event. Triggers can be fired for events such as:
1) Query-related events
2) During validation or navigation events
3) For error or messages
4) During Post or Commit process etc.
Trigger consists of three components:
1) Trigger Type: Events that causes the Trigger to fire. (Pre, Post, When, On, Key Events).
2) Trigger Code: Defines the action that Trigger should perform.
3) Trigger Scope: Defines the level of the Trigger (Form, Block or Item level)
Pre-Event: Fires before an action is performed.
Post-Event: Fires just after an action has performed.
When-Event: Fires in addition to standard Processing. Is used to augment functionality. On-Event: Fires in place of standard processing. Used to replace or bypass a process. Also used for suppressing errors and messages.
Key-Triggers: Fires in place of standard action of a function key. Fires when the operator presses the associated key or key-sequence.
Trigger is divided into following categories:
1) Block Processing Triggers: When-Clear-Block, When-Create-Record, When-Database-record, When-Remove-Record.
2) Interface Event Triggers: When-Button-Pressed, When-Checkbox-Changed, When-Radio-Changed, When-List-Changed, When-Image-Activated, When-Image-Pressed, When-Mouse-Click, When-Mouse-DoubleClick, When-Mouse-Down, When-Mouse-up, When-Mouse-Move, When-Mouse-Enter, When-Mouse-Leave, When-Timer-Expired, When-Window-Activated, When-Window-Closed, When-Window-Deactivated, When-Window-Resized.
3) Key Triggers: Function Key, Key-Fn, Key-Others.
4) Master-Detail Triggers: On-Check-Delete-Master, On-Clear-Details, On-Populate-Details.
5) Message-Handling Triggers: On-Error, On-Message.
6) Navigational Triggers: Pre-Form, Pre-Block, Pre-Record, Pre-Text-Item, Post-Form, Post-Block, Post-Record, Post-Text-Item, When-Form-Navigate, When-New-Form-Instance, When-New-Block-Instance, When-New-Record-Instance, When-New-Item-Instance.
7) Query-Time Triggers: Pre-Query, Post-Query.
8) Transactional Triggers: On-Check-Unique, On-Close, On-Commit, On-Count, On-Fetch, On-Select, On-Delete, On-Insert, On-Update, On-Logon, On-Logout, On-Rollback, Post-Change, Post-Database-Commit, Post-Forms-Commit, Post-Delete, Post-Insert, Post-Update, Post-Select, Post-Fetch, Pre-Delete, Pre-Update, Pre-Insert, Pre-Commit, Pre-Select, Pre-Logon, Pre-Logout.
9) Validation Triggers: When-Validate-Item, When-Validate-Record.
10) User-Named Triggers: Execute_Trigger(‘Trigger_name’)
Question 50: What are System Variables?
System variables are oracle form variables that are used to control the way an aplication behaves.
List of system Variables:
Question 51: What is a difference between Restricted and Unrestricted Built-In Subprograms?
Built-in Subprogram is divided into two categories:
1) Restricted Built-in Subprograms
2) Unrestricted Built-in Subprograms
Restricted Built-In Subprograms:Restricted built-ins affect navigation in your form, either external screen navigation, or internal navigation. You can call these built-ins only from triggers where no internal navigation is occurring. Restricted built-ins cannot be called from the Pre and Post triggers, which fire when Oracle Forms is navigating from object to another. Restricted built-ins can be called from the When triggers that are specific to interface items, such as When-Button-Pressed or When-Checkbox-Changed. Restricted built-ins can also be called from any of the When-New-“Object”-Instance triggers and from key triggers. Examples: Clear_Block, Go_Block, Next_Block, Previous_Block, Clear_Form, Commit_Form, Enter, Exit_Form, Open_form etc.
Unrestricted Built-In Subprograms: Unrestricted built-ins do not affect logical or physical navigation and can be called from any Trigger. Examples:
3) Set and Get Built-ins (Ex: Get_Item_Property, Set_Item_Property)
4) Find Built-ins (Ex: Find_Block, Find_View etc)
5) Call_Form etc.