Data Types are simply enough the types of data a variable or field in a database can store.
Numerical Data types Edit
Numerical data types are used to represent numeric values. These values can be added, subtracted, multiplied, and divided. Also can have other mathematical functions such as Sine performed on them.
Whole Numbers Edit
These numbers are the numbers that do not contain decimal points. Aside from the lack of decimal points, the only restrictions are memory size and whether the number can be negative or not.
These numbers contain decimal points. For doing exponentiation, it is highly recommended to use some type of decimal as negative exponents and fractional exponents usually result in some kind of decimal.
Character data types are any data type that isn't numeric, while these types can be used to store numbers, you can't perform mathematical operations on them in this form. You'd have to convert them to a numeric data type first. Usually in this form the addition operator becomes a concatation operator, meaning that if you have a character variable with the number 1 as its current value and try to add a two to it, the programmer will end up with a 12 instead of a 3. It is possible to write programs to add characters as if they are numbers, but not very efficient.
Usually files or graphics.
User-defined type Edit
|Programming||Character - Floating point Number - User-defined Type - Integer|
|Database||Character - Decimal - Integer - Blob|