is there a link to some standard, universally accepted data types and sizes for common entries such as zip codes, phone numbers etc??? i am getting more involved in database work and i want to avoid problems with my data types... thanks in advance

It depends what type of database you're using. ZIP and Phone numbers would usually be a text based field, such as VARCHAR in MSSQL.

It is largely a matter of personal preference since many options will produce the same results. Sometimes there are small reasons you may use to choose one over the other. For example, I generally use INTEGER for phone numbers keeping a separate fields for area code, exchange, and the last 4 numbers. I do this because it's easier to secure a integer input than it is to secure text. I also find is easier to search by area cosde or exchange in large databases this way.

In the end whatever works is fine, but simply let practice and individual circumstance be your guide.

Phone numbers should not be stored as integers. While it may work in most cases, phone numbers are not really 'numbers' as such - they are strings of numbers. For example, you wouldn't do a calculation on a phone number. Also, what if a phone number starts with a Zero? Store that in a database as an integer, and the database will drop the leading zero and when you retreive it, the phone number will be wrong.

good point regarding the leading zeros.