|DO WHILE allows a group of statements to be executed zero or more times under
control of a condition. Before each execution of the loop, the <expression>
following the while is evaluated. If it has the conditional value true
the statements in the <group head> are executed and control returns to the conditional test.
If it has the value false control passed to the statement following end.
i = -5; do while i<0; output = 'The value is ' || i; i = i+1; end;