PL/SQL Spacing Standards Oracle Tips by Jonathan Ingram

PL/SQL Horizontal Spacing Best Practices Standards

You?ve probably heard of the obfuscated C contest, where the entrants attempt to cram as much code as possible onto a single line that does some type of work while remaining completely unreadable. If you have any experience maintaining code, you?ve probably seen more than a few pieces of code that have a good chance of winning a contest like this. The guidelines presented in this section are an attempt to guide you away from writing hard-to-read code.

?  One of the most important elements in creating readable code is the spacing placed around operators. Below shows common operators and keywords that need to be preceded and followed by a space when they are used in expressions.

Operators and keywords to be preceded and followed by a space in expressions.
+	-	*	/
&	<	>	=
!=	<=	>=	:=
=>	||	..	:
<>	IN	OUT	AND
OR	NOT	NULL

Often more than one of the operators and keywords shown in Table D.3 will be adjacent to each other inside an expression. In this instance, it is recommended that only one space lie between the two operators/identifiers. For example:

  IF (vMajor IS NOT NULL) THEN

?  Spaces should precede and follow character (') literals.

  SELECT first_name || ' ' || middle_name || ' ' || last_name

         'student_name'

  FROM   STUDENTS

  WHERE  ssn = 999999999;

?  Do not leave any blank spaces preceding or following the ** operator.

  nRaisedNum := nNum**nPower;

?  Do not leave blank spaces before or after the plus (+) and minus (-) signs when used as unary operators.

  nNumber := -nSecondNumber;

  nNumber := +nSecondNumber;

?  Do not use spaces between multiple parentheses or semicolons (;). Always precede the first opening parenthesis of a set with a space.

  AND (((x < 5) AND (y < 5))

  OR   ((x > 5) AND (y > 5)));

PL/SQL Vertical Spacing Best Practices Standards

Vertical spacing helps distance elements in the code from one another, reducing the visual clutter above and below statements. To create appropriate vertical spacing for your code, place a blank line in the locations described in the following list:

?  Before lines containing the keywords IF, ELSE, ELSIF, and EXCEPTION. If the line is preceded by a comment, place the blank line before the comment instead of before the line of text.

  --

  -- If the student's grade point average meets the criteria for

  -- mandatory academic counseling, add the student's name and social

  -- security number to the list.

  --

  IF (nRealGPA < 1.5) THEN

   <statements>

  --

  -- We also want to consider students who are failing two or more

  -- classes, even if their GPA is above 1.5.

  --

  ELSIF Has_Two_Fails (nForSSN => nSSN) THEN

     <statements>

  ELSE

     <statements>

  END IF;

?  Before any line containing the LOOP keyword. Do not place a blank line before source code containing the END LOOP keyword. (As with lines of code containing the IF keyword, keep the comments for a line of code with the comment by placing a blank line before the comment.)

  --

  -- For each student returned by the query, add the student's social

  -- security number to the PL/SQL table.

  --

  FOR Students_rec IN Students_cur LOOP

     <statements>

  END LOOP;

?  Before each exception after the first declared within the EXCEPTION section of a PL/SQL block.

  EXCEPTION

    WHEN NO_DATA_FOUND THEN

         <statements>

    WHEN TOO_MANY_ROWS THEN

         <statements>

    WHEN OTHERS THEN

         <statements>

?  Before and after the variable, constant, and type declarations for a PL/SQL block.

  PROCEDURE Update_Student_GPA (nSSN IN     number)

  IS

    <declaration>

    <declaration>

  BEGIN

    <statements>;

  END Update_Student_GPA;

?  Following the declaration of the procedure and its parameters.

  PROCEDURE Update_Student_GPA (nSSN IN     number)

  IS

?  Do not place an empty line before a line containing the END IF keyword. Do place blank lines after the last line of code containing the END IF keyword.

  IF (some expression) THEN

    IF (some expression) THEN

      IF (some expression) THEN

         <statements>

      END IF;

    END IF;

  END IF;

  <statements>

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This is an excerpt from "High Performance Oracle Database Automation", by Jonathan Ingram and Donald K. Burleson, Series Editor.
 

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