Everything is stored in database in SAP system

Note that it is easy to store data in form of SAP database tables as compared to files. You can also access files in SAP system but they are available on file system of SAP Application server and not easy to use with.

With use of ABAP, you can easily raise queries against database tables and it is safe to run queries to get data. SAP has various tools that allow you to work with table entries and also to manage entire landscape easily.
What databases are supported by SAP?

Microsoft SQL Serverwww.microsoft.com
MySQL MaxDBwww.mysql.com
IBM DB2 (various versions)www.ibm.com

Also SAP has its own in-memory computing engine to handle large amount of data in real time with high performance known as SAP HANA.
A database table in SAP system in ABAP Dictionary can have a maximum of 16 characters- it can contain letters, numbers, and underscores, must start with a letter, and can be prefixed by a namespace prefix (/.../) from a prefix namespace. The name is in the namespace of the data types in ABAP Dictionary.

A Database table consists of following fields:

  • A flat, non-nested structure in ABAP Dictionary
  • Technical attributes of the database table
  • Semantic attributes of the database table

You have following types of database table in SAP system:

  • Transparent table
  • Pooled Table
  • Cluster Table

To know more about SAP tables, you can check this SAP link:
Most common type of table in SAP system is “Transparent table”. You can view/change a table in SAP system using T-Code: SE11.