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ABL Reference
ABL Syntax Reference : RELEASE statement
 

RELEASE statement

Verifies that a record complies with mandatory field and unique index definitions. It clears the record from the buffer and unites it to the database if it has been changed.

Syntax

RELEASE record[ NO-ERROR ]
record
The name of a record buffer.
To use RELEASE with a record in a table defined for multiple databases, you must qualify the record's table name with the database name. See the Record phrase reference entry for more information.
NO-ERROR
Suppresses ABL errors or error messages that would otherwise occur and diverts them to the ERROR-STATUS system handle. If an error occurs, the action of the statement is not done and execution continues with the next statement. If the statement fails, any persistent side-effects of the statement are backed out. If the statement includes an expression that contains other executable elements, like methods, the work performed by these elements may or may not be done, depending on the order the AVM resolves the expression elements and the occurrence of the error.
For the RELEASE statement, as an exception to the general rule, if a unique index constraint is violated the NO-ERROR clause is ignored when validating the record. An error is raised before any changes are saved to the record to avoid damaging any indexes.
To check for errors after a statement that uses the NO-ERROR option:
*Check the ERROR-STATUS:ERROR attribute to see if the AVM raised the ERROR condition.
*Check if the ERROR-STATUS:NUM-MESSAGES attribute is greater than zero to see if the AVM generated error messages. ABL handle methods used in a block without a CATCH end block treat errors as warnings and do not raise ERROR, do not set the ERROR-STATUS:ERROR attribute, but do add messages to the ERROR-STATUS system handle. Therefore, this test is the better test for code using handle methods without CATCH end blocks. ABL handle methods used in a block with a CATCH end block raise ERROR and add messages to the error object generated by the AVM. In this case, the AVM does not update the ERROR-STATUS system handle.
*Use ERROR-STATUS:GET-MESSAGE( message-num ) to retrieve a particular message, where message-num is 1 for the first message.
If the statement does not include the NO-ERROR option, you can use a CATCH end block to handle errors raised by the statement.
Some other important usage notes on the NO-ERROR option:
*NO-ERROR does not suppress errors that raise the STOP or QUIT condition.
*A CATCH statement, which introduces a CATCH end block, is analogous to a NO-ERROR option in that it also suppresses errors, but it does so for an entire block of code. It is different in that the error messages are contained in a class-based error object (generated by the AVM or explicitly thrown), as opposed to the ERROR-STATUS system handle. Also, if errors raised in the block are not handled by a compatible CATCH block, ON ERROR phrase, or UNDO statement, then the error is not suppressed, but handled with the default error processing for that block type.
*When a statement contains the NO-ERROR option and resides in a block with a CATCH end block, the NO-ERROR option takes precedence over the CATCH block. That is, an error raised on the statement with the NO-ERROR option will not be handled by a compatible CATCH end block. The error is redirected to the ERROR-STATUS system handle as normal.
*If an error object is thrown to a statement that includes the NO-ERROR option, then the information and messages in the error object will be used to set the ERROR-STATUS system handle. This interoperability feature is important for those integrating code that uses the traditional NO-ERROR technique with the newer, structured error handling that features error objects and CATCH end blocks.

Example

The following example uses a browse widget to scan Customer records. Records within the browse are read with NO-LOCK. If you choose the Update Customer button, the CHOOSE trigger starts a transaction and applies an EXCLUSIVE-LOCK to the Customer record. When you have completed any updates, the procedure displays the new values in the browse widget and then executes a RELEASE statement. This ensures that the lock is released when the transaction ends.
r-rels.p
DEFINE VARIABLE methRtn   AS LOGICAL NO-UNDO.
DEFINE VARIABLE curr-cust AS ROWID   NO-UNDO.

DEFINE BUTTON upd-cust LABEL "Update Customer".
DEFINE BUTTON exit-app LABEL "Exit".

DEFINE QUERY seq-cust FOR customer.
DEFINE BROWSE brow-cust QUERY seq-cust
  DISPLAY Customer.CustNum Customer.Name WITH 10 DOWN.

FORM
  upd-cust exit-app SKIP(1)
  brow-cust
  WITH FRAME main-frame.
FORM
  Customer EXCEPT Customer.Comments
  WITH FRAME curr-frame COLUMN 40.

OPEN QUERY seq-cust FOR EACH Customer.

ON VALUE-CHANGED OF brow-cust DO:
  DISPLAY Customer EXCEPT Customer.Comments
    WITH FRAME curr-frame SIDE-LABELS.
  curr-cust = ROWID(Customer).
END.

ON CHOOSE OF upd-cust DO: /* TRANSACTION */
  FIND Customer WHERE ROWID(Customer) = curr-cust EXCLUSIVE-LOCK.
  UPDATE Customer WITH FRAME cust-frame VIEW-AS DIALOG-BOX
  TITLE "Customer Update".
  methRtn = brow-cust:REFRESH().
  DISPLAY Customer EXCEPT Customer.Comments
    WITH FRAME curr-frame SIDE-LABELS.
  RELEASE Customer.
END.

ENABLE ALL WITH FRAME main-frame.
APPLY "VALUE-CHANGED" TO brow-cust.
PAUSE 0 BEFORE-HIDE.
WAIT-FOR CHOOSE OF exit-app OR WINDOW-CLOSE OF DEFAULT-WINDOW.
If you omit the RELEASE statement in this example, the EXCLUSIVE-LOCK is downgraded to a SHARE-LOCK at the end of the transaction. This prevents other uses from updating that record. The SHARE-LOCK is released when you change the iteration of the browse.

Notes

*An ERROR occurs if the validation of the record fails. This can happen only with newly created records.
*If a record has been modified, the RELEASE statement causes a WRITE event and fires any related WRITE trigger to execute. All WRITE triggers execute before the record is actually written. If a WRITE trigger fails (or executes a RETURN statement with the ERROR option), the corresponding record is not written or released and the ERROR condition is raised for the RELEASE statement.
*See OpenEdge Getting Started: ABL Essentials for more information on transactions.