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LEAVE

Available in: PSQL

Added in: 1.5

Changed in: 2.0

Description

LEAVE immediately terminates the innermost WHILE or FOR loop. With the optional label argument introduced in Firebird 2.0, LEAVE can break out of surrounding loops as well. Execution continues with the first statement after the outermost terminated loop.

Syntax

 [label:]
 {FOR | WHILE} ... DO
    ...
    (possibly nested loops, with or without labels)
    ...
    LEAVE [label];

Example

If an error occurs during the insert in the example below, the event is logged and the loop terminated. The program continues at the line of code reading c = 0;

 while (b < 10) do
 begin
   insert into Numbers(B) values (:b);
   b = b + 1;
   when any do
   begin
     execute procedure log_error (current_timestamp, 'Error in B loop');
     leave;
   end
 end
 c = 0;

The next example uses labels. Leave LoopA terminates the outer loop, leave LoopB the inner loop. Notice that a plain leave would also suffice to terminate the inner loop.

 stmt1 = 'select Name from Farms';
 LoopA:
 for execute statement :stmt1 into :farm do
 begin
   stmt2 = 'select Name from Animals where Farm = ''';
   LoopB:
   for execute statement :stmt2 || :farm ||  into :animal do
   begin
     if (animal = 'Fluffy') then leave LoopB;
     else if (animal = farm) then leave LoopA;
     else suspend;
   end
 end

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