Comments on: How-To MySQL CREATE TABLE Example showing default values, NULL values and comments

By: Anonymous

Anonymous — Sun, 18 Dec 2011 19:38:00 +0000

how to add default value with alter table?

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By: Mohamed

Mohamed — Thu, 15 Sep 2011 18:00:00 +0000

mmmm

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By: Arunstalins

Arunstalins — Wed, 14 Sep 2011 05:37:00 +0000

thakqqqqqqqqq

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By: canlı maç izle

canlı maç izle — Thu, 03 Mar 2011 11:43:00 +0000

thanks this is very helpful

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By: Kevin Bedell

Kevin Bedell — Tue, 11 Jan 2011 15:39:00 +0000

The benefit of having NULL or NOT NULL values comes from allowing the database to enforce constraints on the data to match your application.

For example, if you have a CUSTOMER table that requires a particular ‘customer_type’ attribute, you can make the ‘customer_attribute’ column ‘NOT NULL’ — meaning the data cannot be saved into the database unless a value for that column is provided.

Sometimes, however, having a value be NULL is fine — for example, if the same CUSTOMER table has both ‘work_phone’ and ‘home_phone’ columns. Maybe they aren’t both required — so those values can be allowed to be NULL.

I hope this answers your questions – thanks for reading!

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By: Praveena

Praveena — Sun, 09 Jan 2011 14:23:00 +0000

What are the benefits of using either NULL or NOT NULLs? thanks

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