Comments

Comments let you include arbitrary text within your code to explain what the code does. You can also disable obsolete or unfinished pieces of code by turning them into comments.

PL/SQL supports two comment styles: single-line and multi-line. A double hyphen (- -) anywhere on a line (except within a character literal) turns the rest of the line into a comment. Multi-line comments begin with a slash-asterisk (/*) and end with an asterisk-slash (*/). For more information, see "Comments".

Syntax

Description of the illustration comment.gif

Usage Notes

Single-line comments can appear within a statement at the end of a line.

You can include single-line comments inside multi-line comments, but you cannot nest multi-line comments.

You cannot use single-line comments in a PL/SQL block that will be processed dynamically by an Oracle Precompiler program. End-of-line characters are ignored, making the single-line comments extend to the end of the block. Instead, use multi-line comments.

While testing or debugging a program, you might want to disable a line of code. The following example shows how you can "comment-out" the line:

-- UPDATE department SET location_id = my_loc WHERE department_id = my_deptno;

You can use multi-line comment delimiters to comment-out whole sections of code.

Examples

The following examples show various comment styles:

DECLARE
   area NUMBER; pi NUMBER; radius NUMBER;
BEGIN
   -- Compute the area of a circle
   area := pi * radius**2;  -- pi is approx. 3.14159

   /*
   Compute the area
   of a circle.
   */
   area := pi /* pi is approx. 3.14159 */ * radius**2;  
END;
/