Ask any IT consultant what differentiates a good programmer from a bad one, and they will answer that good programmers always comment their code. Adding comments to code promotes readability and aids in logic comprehension and code maintenance.
Comments are strictly informational and do not enforce any conditions or behavioral logic or data. In fact, the Oracle compiler ignores all comments.
Comments are used to describe the purpose and use of each code segment. PL/SQL supports two comment styles.
Single-line comments
Single-line comments begin with a double hyphen (--) anywhere on a line and can extend to the end of line.

-- This is an example of a comment

Multiline comments begin with /* and end with /. They can span multiple lines. Multiline comments can be used to comment out whole sections of code.
/* This is an example of a comment that
spans more than one line. */

Here is a good example of a well-documented PL/SQL block. Click the View Code link below .
View Code
Now that you have learned about PL/SQL blocks as well as literals, identifiers, and comments, let’s use an instructional simulation to build a nested PL/SQL block.
The following simulation demonstrates the creation of a PL/SQL block that declares a variable as a number. This variable is assigned the value 42. This block includes a nested block that converts this number as a string and displays the values using
Adding Comments