OpenEdge Development:<br />Progress 4GL Reference FIRST function

Release 10.1A: OpenEdge Development:
Progress 4GL Reference

FIRST function

Returns a TRUE value if the current iteration of a DO, FOR EACH, or REPEAT . . . BREAK block is the first iteration of that block.

Syntax
FIRST ( break-group ) 
break-group
The name of a field or expression you name in the block header with the BREAK BY option.
Example

The r-first.p procedure displays the order number, order-lines on the order, the extended price of each order-line, and a total order value for each order record:
r-first.p
DEFINE VARIABLE order-value AS DECIMAL LABEL "Order-value".

FOR EACH order:
  DISPLAY order-num.
  FOR EACH order-line OF order BREAK BY qty * price:
    IF FIRST(qty * price) THEN order-value = 0.
    order-value = order-value + qty * price.
    DISPLAY line-num item-num qty * price 
      LABEL "Extended-price".
  END.
  DISPLAY order-value.
END.  
Because the inner FOR EACH block iterates until Progress reads all the order-lines, the procedure must set the order-value variable to 0 each time a new order is used in that block. The FIRST function uses the (qty * price) expression as the break-group to keep track of whether or not the current iteration is the first iteration of the FOR EACH block.

See also

DO statement, FIRST-OF function, FOR statement, LAST function, LAST-OF function, REPEAT statement