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. 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', ...)

Answer 2

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 3

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.