For more information on creating appliations with the Perl DBI that access DB2 databases, see Programming in Perl . The products vary in how SQL statements are developed and the degree of logic that can be introduced. Depending on your needs, this approach may meet your requirements to access data. This book does not provide further information on query products. One traditional area of application logic is validating and protecting data integrity by controlling the values allowed in the database.
Applications have logic that specifically checks data values as they are entered for validity.
There are several different ways of providing these same capabilities in DB2, but from within the database. The database stores every data element in a column of a table, and defines each column with a data type. This data type places certain limits on the types of values for the column. For example, an integer must be a number within a fixed range. DB2 includes a set of built-in data types with defined characteristics and behaviors.