The amount of effort to type the ‘–‘ signs for a single-line comment increases dramatically as the number of continuous lines to be commented out grows. What if we wanted to disable the last 300 lines of code? Typing ‘/*’ and ‘*/’ signs one time each, is definitely easier than typing the ‘–‘ sign 300 times to achieve the exact same result. Unlike the double hyphen, which can only instruct SQL Server to ignore one line of code at a time, the ‘/*’ ‘*/’ signs (delimiters) are more efficient for multi-line commenting as there can be an infinite number of lines of code between the opening and closing delimiters.
We have attempted to explain the same subject in simple words over in following video.
Get the book for yourself and your friend. This is just a reference everyone must have it.
Read the related blog post: SQL Basics: Code Comments – Day 4 of 10
Reference: Pinal Dave (http://blog.sqlauthority.com)