When should I nest PL/SQL BEGIN…END blocks?

Question

I\'ve been somewhat haphazardly grouping subsections of code in BEGIN...END blocks when it seems right. Mostly when I\'m working on a longer stored procedure and there\'s a

Answer 1

I tend to nest blocks when I want to create procedures that are specific to data that only exists within the block. Here is a contrived example:

BEGIN
  FOR customer IN customers LOOP
    DECLARE

      PROCEDURE create_invoice(description VARCHAR2, amount NUMBER) IS
      BEGIN
        some_complicated_customer_package.create_invoice(
            customer_id => customer.customer_id,
            description => description,
            amount => amount
          );
      END;

    BEGIN

      /* All three calls are being applied to the current customer,
         even if we're not explicitly passing customer_id.
       */
      create_invoice('Telephone bill',  150.00);
      create_invoice('Internet bill',   550.75);
      create_invoice('Television bill', 560.45);

    END;
  END LOOP;
END;

Granted, it's not usually necessary, but it has come in really handy when a procedure can be called from many locations.