Commenting Your Scripts
If you write extensive scripts, you should write extensive comments. In fact, any time you write a script, no matter how short, consider including a few comments to explain the purpose of the script.
Comments may be placed in a script using any of the following three methods:
By using the REMARK command
By using double-hyphen characters
By delimiting the comment by /* and */
Each method works just a bit differently from the others. You will probably find yourself gravitating towards the /*...*/ and — delimiters. The REMARK command is cumbersome, and consequently isn’t used very often.
The REMARK Command
The REMARK command may be used to place comments in a SQL script. Any text on the same line following the REMARK command is considered a comment. The REMARK command may also be abbreviated to REM, as the following example shows:
REMARK This is a comment. REM This is a comment too.
SQL*Plus does not look for substitution variables in the text following a REMARK command, so you are free to use ampersands, and any other characters you like, in your comments.
The /* and */ Delimiters
The /* and */ delimiters are familiar to many programmers, and may also be used to delimit comments in SQL*Plus. Comments created using this method may span multiple lines, for example:
/* This is the second line of a comment. This is the third line. */
You can also use /* and */ to add comments to SQL queries, for example:
SELECT * FROM employee WHERE /* employees are current */ SYSDATE ...