Basically SAP, an enterprise application is made up of programs together with the data used and formed by programs. The data are organized in a meaningful way within the database, making it easy for the programs to access and find the data necessary to do something useful like run a financial report or create a sales order. Both the programs as well as data exist in the same database in the case of an SAP component or products such as ECC. Normally each and every component has its own database a production system landscape composed of SAP ECC, SAP Business Warehouse (BW), and SAP Customer Relationship Management (CRM) consists of three production databases.
Essentially database is an electronic filing system that houses a collection of information organized in such a way that allows a computer program to find preferred pieces of data in a rapid way. A database is composed of tables, columns (called fields), and rows (called records or data). The fundamental structure of a database is same as the Microsoft Excel spreadsheet wherein columns (fields) store row after row of records (data). The difference between a database and a spreadsheet is simply the databases that contain multiple tables are connected to one another through relationships.
Database structure is an alternative technical term that does not need to concern with you, but are important nonetheless. Structures are triggered and are very well defined in the ABAP/4 Data Dictionary and have only temporary data. The database plays a key role in each SAP system, as it houses all the data that are used by that SAP component or product specifically. Numerous brands of databases exist, making it easier for an IT shop to opt for a database vendor with which they are almost well-known. Moreover, it is imperative to note that not all database vendors and versions are supported by SAP. Rather it tends to stick with the market leaders, over the years adding and removing support for certain vendors.
Database tables in an RDBMS are obligatory to hold a unique field that distinguishes one particular record separately from others found in the database. This unique field is called a primary key and is composed of one or more fields that make each and every record in a database as a unique one.
Use the primary key field in one table for linking it with another. The common link field in the other table is usually not the primary key in the other table: and is known as a foreign key.
The SAP system contains lots of types of constructs along with structures inside the R/3 Data Dictionary (DDIC). The majority of these constructs tend to be very technical.
SAP uses another concept called transparent tables, which are SAP database tables that contain only data at runtime. When a table is activated in the ABAP/4 Data Dictionary, a transparent table is created automatically in the database. This transparent table encloses the same name as your database table contained in the ABAP/4 Dictionary. Each of its fields contains the same names as their database counterparts though the sequence of the fields might get varied. This unstable field sequence makes it possible to insert new fields into the table without having to convert it, all of which pays a way for more rapid access to data during runtime.