Which data types should I use?

Question

I am unsure of which data types to use for the following attributes:

• A phone number (which is made up of 10 numbers)

• A client name

• A numeric product ID that acts as a Primary Key

• The location/state of the client (which only has 1 out of 8 possible values)

Im not sure of whether to use CHAR or VARCHAR for some of these, or if there is another type I should use.

Answer 1

1. INTEGER (Always used for numeric numbers) (If you are allowing "+" & etc. use VARCHAR)
2. CHAR (for characters)
3. INTEGER (as mentioned above)
4. VARCHAR (It accepts both the character and the number)

Note: You should use "varchar" for all you needs.

Answer 2

Understanding the difference between Char, Varchar will help you out.

• Char is fixed length.
• Varchar is variable-length. So in case, you have some fixed length variables like Gender, you can go with char, If you have some variable length variable like Name in your case, you can go with Varchar.

Answer 3

1. phone number -> decimal(10, 0)
2. name -> varchar(length)
3. productId -> integer unsigned (you can use autoincrement)
4. location -> enum('possible value 1', 'possible value 2', ...)