Basic Data Types
The following sections discuss the basic data types supported by ANSI SQL. Data types are characteristics of the data itself, whose attributes are placed on fields within a table. For example, you can specify that a field must contain numeric values, disallowing the entering of alphanumeric strings. After all, you would not want to enter alphabetic characters in a field for a dollar amount.
Every implementation of SQL seems to have its own specific data types. The use of implementation-specific data types is necessary to support the philosophy of each implementation on how to handle the storage of data. However, the basics are the same among all implementations.
The very basic data types, as with most other languages, ...