System Variables Toutorial

System Variables

2.1 About System Variables

A system variable is an Oracle Forms variable that keeps track of an internal Oracle Forms state. You can reference the value of a system variable to control the way an application behaves.

Oracle Forms maintains the values of system variables on a per form basis. That is, the values of all system variables correspond only to the current form. The following list presents the names of the available system variables

2.1.1 List of system variables

2.1.1.1 SYSTEM.BLOCK_STATUS

Represents the status of the block where the cursor is located, or the current block during trigger processing. The value can be one of three character strings:

• CHANGED -Indicates that the block contains at least one Changed record.

• NEW - Indicates that the block contains only New records.

• QUERY - Indicates that the block contains only Valid records that have been retrieved from the database.

2.1.1.2 SYSTEM.COORDINATION_OPERATION

This system variable works with its companion SYSTEM.MASTER_BLOCK to help an On-Clear-Details trigger determine what type of coordination-causing operation fired the trigger, and on which master block of a master-detail relation.

2.1.1.3 SYSTEM.CURRENT_BLOCK

The value that the SYSTEM.CURRENT_BLOCK system variable represents depends on the current navigation unit:

• If the current navigation unit is the block, record, or item (as in the Pre- and Post- Item, Record, and Block triggers), the value of SYSTEM.CURRENT_BLOCK is the name of the block that Oracle Forms is processing or that the cursor is in.

• If the current navigation unit is the form (as in the Pre- and Post-Form triggers), the value of SYSTEM.CURRENT_BLOCK is NULL.

The value is always a character string.

Note: SYSTEM.CURRENT_BLOCK is included for compatibility with previous versions. Oracle Corporation recommends that you use SYSTEM.CURSOR_BLOCK and SYSTEM.TRIGGER_BLOCK instead.

2.1.1.4 SYSTEM.CURRENT_DATETIME

Is a variable representing the operating system date. The value is a CHAR string in the following format:

DD-MON-YYYY HH24:MI:SS

2.1.1.5 SYSTEM.CURRENT_FORM

Represents the name of the form that Oracle Forms is executing. The value is always a character string.

2.1.1.6 SYSTEM.CURRENT_ITEM

The value that the SYSTEM.CURRENT_ITEM system variable represents depends on the current navigation unit:

• If the current navigation unit is the item (as in the Pre- and Post-Item triggers), the value of SYSTEM.CURRENT_ITEM is the name of the item that Oracle Forms is processing or that the cursor is in. The returned item name does not include a block name prefix.

• If the current navigation unit is the record, block, or form (as in the Pre- and Post- Record, Block, and Form triggers), the value of SYSTEM.CURRENT_ITEM is NULL.

The value is always a character string.

Note: SYSTEM.CURRENT_ITEM is included for compatibility with previous versions. Oracle Corporation recommends that you use SYSTEM.CURSOR_ITEM or SYSTEM.TRIGGER_ITEM instead.

2.1.1.7 SYSTEM.CURRENT_VALUE

Represents the value of the item that is registered in SYSTEM.CURRENT_ITEM.

The value is always a character string.

Note: SYSTEM.CURRENT_VALUE is included for compatibility with previous versions. Oracle Corporation recommends that you use SYSTEM.CURSOR_ITEM and SYSTEM.CURSOR_VALUE instead.

2.1.1.8 SYSTEM.CURSOR_BLOCK

The value that the SYSTEM.CURSOR_BLOCK system variable represents depends on the current navigation unit:

• If the current navigation unit is the block, record, or item (as in the Pre- and Post- Item, Record, and Block triggers), the value of SYSTEM.CURSOR_BLOCK is the name of the block where the cursor is located. The value is always a character string.

• If the current navigation unit is the form (as in the Pre- and Post-Form triggers), the value of SYSTEM.CURSOR_BLOCK is NULL.

2.1.1.9 SYSTEM.CURSOR_ITEM

Represents the name of the block and item, block.item, where the input focus (cursor) is located.

The value is always a character string.

2.1.1.10 SYSTEM.CURSOR_RECORD

Represents the number of the record where the cursor is located. This number represents the record's current physical order in the block's list of records. The value is always a character string.

2.1.1.11 SYSTEM.CURSOR_VALUE

Represents the value of the item where the cursor is located. The value is always a character string.

2.1.1.12 SYSTEM.CUSTOM_ITEM_EVENT

Stores the name of the event fired by a VBX control.

2.1.1.13 SYSTEM.CUSTOM_ITEM_EVENT_PARAMETERS

Stores the supplementary arguments for an event fired by a VBX control.

2.1.1.14 SYSTEM.DATE_THRESHOLD*

Represents the database date requery threshold. This variable works in conjunction with the three system variables $$DBDATE$$, $$DBDATETIME$$, and $$DBTIME$$, and controls how often Oracle Forms synchronizes the database date with the RDBMS. The value of this variable must be specified in the following format: MI:SS .

Because frequent RDBMS queries can degrade performance, it is best to keep this value reasonably high. However, keep in mind that if the value is not synchronized often enough, some time discrepancy can occur. In addition, if you are building a client-server application, the performance implications of SYSTEM.DATE_THRESHOLD could vary depending on the complexity of your network configuration.

2.1.1.15 SYSTEM.EFFECTIVE_DATE*

Represents the effective database date. The variable value must always be in the following format:

DD-MON-YYYY HH24:MI:SS .

2.1.1.16 SYSTEM.EVENT_WINDOW

The SYSTEM.EVENT_WINDOW system variable represents the name of the last window that was affected by an action that caused one of the window event triggers to fire. The following triggers cause this variable to be updated:

• WHEN-WINDOW-ACTIVATED

• WHEN-WINDOW-CLOSED

• WHEN-WINDOW-DEACTIVATED

• WHEN-WINDOW-RESIZED

From within these triggers, you can assign the value of the variable to any of the following:

• global variable

• parameter

• variable

• item, including a null canvas item

2.1.1.17 SYSTEM.FORM_STATUS

Represents the status of the current form. The value can be one of three character strings:

• CHANGED - Indicates that the form contains at least one block with a Changed record. The value of SYSTEM.FORM_STATUS becomes CHANGED only after at least one record in the form has been changed and the associated navigation unit has also changed.

• NEW - Indicates that the form contains only New records.

• QUERY - Indicates that a query is open. The form contains at least one block with QUERY records and no blocks with CHANGED records.

2.1.1.18 SYSTEM.LAST_FORM

Represents the form module ID of the previous form in a multi-form application, where multiple forms have been invoked using OPEN_FORM. The value can be one of two character strings: either the form module ID or NULL.

2.1.1.19 SYSTEM.LAST_QUERY

Represents the query SELECT statement that Oracle Forms most recently used to populate a block during the current Run form session. The value is always a character string.

2.1.1.20 SYSTEM.LAST_RECORD

Indicates whether the current record is the last record in a block's list of records. The value is one of the following two CHAR values:

• TRUE - Indicates that the current record is the last record in the current block's list of records.

• FALSE - Indicates that the current record is not the last record in the current block's list of records.

2.1.1.21 SYSTEM.MASTER_BLOCK

This system variable works with its companion SYSTEM.COORDINATION_OPERATION to help an On-Clear-Details trigger determine what type of coordination-causing operation fired the trigger, and on which master block of a master-detail relation. The values of the two system variables remain constant throughout the clearing phase of any block synchronization. SYSTEM.MASTER_BLOCK represents the name of the driving master block, and SYSTEM.COORDINATION_OPERATION represents the coordination-causing event that occurred on the master block.

More details are in the description for SYSTEM.COORDINATION_OPERATION.

2.1.1.22 SYSTEM.MESSAGE_LEVEL*

Represents one of the following message severity levels: 0, 5, 10, 15, 20, or 25. The value is always a character string.

During a Runform session, Oracle Forms suppresses all messages with a severity level that is the same or lower (less severe) than the indicated severity level.

Assign a value to the SYSTEM.MESSAGE_LEVEL system variable with standard PL/SQL syntax:

:System.Message_Level := value;

The legal values for SYSTEM.MESSAGE_LEVEL are 0, 5, 10, 15, 20, and 25. Oracle Forms does not suppress prompts or vital error messages, no matter what severity level you select.

2.1.1.23 SYSTEM.MODE

SYSTEM.MODE indicates whether the form is in Normal, Enter Query, or Fetch Processing mode. The value is always a character string.

• NORMAL - Indicates that the form is currently in normal processing mode.

• ENTER-QUERY - Indicates that the form is currently in Enter Query mode.

• QUERY - Indicates that the form is currently in fetch processing mode, meaning that a query is currently being processed.

2.1.1.24 SYSTEM.MOUSE_BUTTON_PRESSED

Indicates the number of the button that was clicked. Mouse button support is limited to buttons 1 and 2 (left or middle) on a three button mouse. The value is always a character string.

2.1.1.25 SYSTEM.MOUSE_BUTTON_SHIFT_STATE

Indicates the key that was pressed during the click, such as SHIFT, ALT, or CONTROL. The value is always a character string.

2.1.1.26 SYSTEM.MOUSE_CANVAS

If the mouse is in a canvas, SYSTEM.MOUSE_CANVAS represents the name of that canvas as a CHAR value. If the mouse is in an item, this variable represents the name of the canvas containing the item.

SYSTEM.MOUSE_CANVAS is NULL if:

• the mouse is not in a canvas

• the platform is non-GUI

2.1.1.27 SYSTEM.MOUSE_FORM

If the mouse is in a form module, SYSTEM.MOUSE_FORM represents the name of that form module as a CHAR value. For example, if the mouse is in Form_Module1, the value for SYSTEM.MOUSE_ITEM is FORM_MODULE1.

Note: SYSTEM.MOUSE_FORM is NULL if the platform is not a GUI platform.

2.1.1.28 SYSTEM.MOUSE_ITEM

If the mouse is in an item, SYSTEM.MOUSE_ITEM represents the name of that item as a CHAR value. For example, if the mouse is in Item1 in Block2, the value for SYSTEM.MOUSE_ITEM is :BLOCK2.ITEM1.

SYSTEM.MOUSE_ITEM is NULL if:

• the mouse is not in an item

• the platform is not a GUI platform

2.1.1.29 SYSTEM.MOUSE_RECORD

If the mouse is in a record, SYSTEM.MOUSE_RECORD represents that record's record number as a CHAR value.

Note: SYSTEM.MOUSE_RECORD is 0 if the mouse is not in an item (and thus, not in a record).

2.1.1.30 SYSTEM.MOUSE_RECORD_OFFSET

If the mouse is in a record, SYSTEM.MOUSE_RECORD_OFFSET represents the offset from the first visible record as a CHAR value.

For example, if the mouse is in the second of five visible records in a multi-record block, SYSTEM.MOUSE_RECORD_OFFSET is 2. (SYSTEM.MOUSE_RECORD_OFFSET uses a 1-based index).

Note: SYSTEM.MOUSE_RECORD_OFFSET is 0 if the mouse is not in an item (and thus, not in a record).

2.1.1.31 SYSTEM.MOUSE_X_POS

Represents (as a CHAR value) the x coordinate of the mouse in the units of the current form coordinate system. If the mouse is in an item, the value is relative to the upper left corner of the item's bounding box. If the mouse is on a canvas, the value is relative to the upper left corner of the canvas.

Note: SYSTEM.MOUSE_X_POS is always NULL on character mode platforms.

2.1.1.32 SYSTEM.MOUSE_Y_POS

Represents (as a CHAR value) the y coordinate of the mouse, using units of the current coordinate system. If the mouse is in an item, the value is relative to the upper left corner of the item's bounding box. If the mouse is on a canvas, the value is relative to the upper left corner of the canvas.

Note: SYSTEM.MOUSE_Y_POS is always NULL on character mode platforms.

2.1.1.33 SYSTEM.RECORD_STATUS

Represents the status of the record where the cursor is located. The value can be one of four character strings:

• CHANGED - Indicates that a queried record's validation status is Changed.

• INSERT - Indicates that the record's validation status is Changed and that the record does not exist in the database.

• NEW - Indicates that the record's validation status is New.

• QUERY - Indicates that the record's validation status is Valid and that it was retrieved from the database.

2.1.1.34 SYSTEM.SUPPRESS_WORKING*

suppresses the "Working..." message in Runform, in order to prevent the screen update usually caused by the display of the "Working..." message. The value of the variable is one of the following two CHAR values:

• TRUE - Prevents Oracle Forms from issuing the "Working..." message.

• FALSE - Allows Oracle Forms to continue to issue the "Working..." message.

2.1.1.35 SYSTEM.TRIGGER_BLOCK

Represents the name of the block where the cursor was located when the current trigger initially fired. The value is NULL if the current trigger is a Pre- or Post-Form trigger. The value is always a character string.

2.1.1.36 SYSTEM.TRIGGER_ITEM

Represents the item (BLOCK.ITEM) in the scope for which the trigger is currently firing. When referenced in a key trigger, it represents the item where the cursor was located when the trigger began. The value is always a character string.

2.1.1.37 SYSTEM.TRIGGER_RECORD

Represents the number of the record that Oracle Forms is processing. This number represents the record's current physical order in the block's list of records. The value is always a character string.

All system variables, except the four indicated with an asterisk (*), are read-only variables. These four variables are the only system variables to which you can explicitly assign values.

2.1.2 Date and Time System Default Values

Oracle Forms also supplies six special default values -- $$DATE$$, $$DATETIME$$, $$TIME$$, $$DBDATE$$, $$DBDATETIME$$, and $$DBTIME$$ -- that supply date and time information and have special restrictions on their use:

• If you're building client/server applications, consider the performance implications of going across the network to get date and time information.

• If you're accessing a non-ORACLE datasource, avoid using $$DBDATE$$ and $$DBDATETIME$$. Instead, use a When-Create-Record trigger to select the current date in a datasource-specific manner.

• Use $$DATE$$, $$DATETIME$$, and $$TIME$$ to obtain the local system date/time; use $$DBDATE$$, $$DBDATETIME$$, and $$DBTIME$$ to obtain the database date/time, which may differ from the local system date/time if, for example, you're connecting to a remote database in a different time zone.

• Use these variables only to set the value of the Default Value, Range Low Value or Range High Value property.

2.1.2.1 $$DATE$$

Retrieves the current operating system date. You can use $$DATE$$ to designate a default value or range for a text item using the Default or Range property. The text item must be of the CHAR, DATE, or DATETIME data type. You also can use $$DATE$$ as a default value for form parameters. In this case, the parameter's value is computed once, at form startup.

2.1.2.2 $$DATETIME$$

Retrieves the current operating system date and time. You can use $$DATETIME$$ to designate a default value or range for a text item using the Default or Range property. The text item must be of the CHAR or DATETIME data type. You also can use $$DATETIME$$ as a default value for form parameters. In this case, the parameter's value is computed once, at form startup.

The difference between $$DATE$$ and $$DATETIME$$ is that the time component for $$DATE$$ is always fixed to 00:00:00, compared to $$DATETIME$$, which includes a meaningful time component, such as 09:17:59.

Note: Do not use $$DATETIME$$ instead of $$DATE$$ unless you plan to specify the time component. If, for example, you use $$DATETIME$$ with the default DATE format mask of DD-MON-YY, you would be committing values to the database that the user would not see, because the format mask does not include a time component. Then, because you had committed specific time information, when you later queried on date, the values would not match and you would not return any rows.

2.1.2.3 $$DBDATE$$

Retrieves the current database date. You can use $$DBDATE$$ to designate a default value or range for a text item using the Default or Range property. The text item must be of the CHAR, DATE, or DATETIME data type.

2.1.2.4 $$DBDATETIME$$

Retrieves the current date and time from the local database. You can use $$DBDATETIME$$ to designate a default value or range for a text item using the Default or Range property. The text item must be of the CHAR or DATETIME data type.

2.1.2.5 $$DBTIME$$

Retrieves the current time from the local database. You can use $$DBTIME$$ to designate a default value or range for a text item using the Default or Range property. The text item must be of the CHAR or TIME data type.

2.1.2.6 $$TIME$$

Retrieves the current operating system time. You can use $$TIME$$ to designate a default value or range for a text item using the Default or Range property. The text item must be of the CHAR or TIME data type.

You also can use $$TIME$$ as a default value for form parameters. In this case, the parameter's value is computed once, at form startup.

2.1.3 Local Variables

Because system variables are derived, if the value is not expected to change over the life of the trigger, you can save the system value in a local variable and use the local variable multiple times.