What is numerical data?

Another common type of data is numerical data — data that is stored as a number. Decimal numbers (for example, 10.5, 2.34567, 23456.7) can be stored as well as integers (for example, 1, 2, 248). When data is stored as a number, it can be used in numerical operations, such as adding, subtracting, and squaring. If data isn’t used for numerical operations, however, storing it as a character string is better because the programmer will be using it as a character string. No conversion is required. For example, you probably won’t want to add the digits in the users’ phone numbers, so phone numbers should be stored as character strings.

MySQL stores positive and negative numbers, but you can tell MySQL to store only positive numbers. If your data is never negative, store the data as unsigned (without using a + or – sign before the number). For example, a city population or the number of pages in a document can never be negative. MySQL provides a specific type of numeric column called an auto-increment column. This type of column is automatically filled with a sequential number when no specific number is provided. For example, when a table row is added with 5 in the auto-increment column, the next row is automatically assigned 6 in the column, unless a different number is specified. Auto-increment columns are useful when unique numbers are needed, such as a product number or an order number.