As we know, a database is made up of tables where we store cataloged records based on different fields (characteristics).
A previous aspect to consider is the nature of the values that we introduce in those fields. Since a database works with all types of information, it is important to specify what type of value we are introducing in order to, on the one hand, facilitate the search later and, on the other, optimize memory resources.
Each database introduces types of field values that are not necessarily present in others. However, there is a set of types that are represented in all of these bases. These common types are as follows:
alphanumeric
They contain figures and letters. They have a limited length (255 characters)
numeric
There are several types, mainly integers (without decimals) and real (with decimals).
Booleans
They have two forms: True and False (Yes or No)
dates
They store dates facilitating their exploitation later. Storing dates in this way makes it possible to sort the records by date or calculate the days between one date and another…
memos
They are alphanumeric fields of unlimited length. They have the drawback of not being able to be indexed (we will see later what this means).
Autoincrementing
They are integer numeric fields that increment their value by one unit for each record entered. Its usefulness is more than obvious: Serve as an identifier since they are unique to a registry.
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