One of the most powerful features of Delphi is the way you can work with databases.
Delphi offers (certainly version 5) many way's to write complex database applications.
This papers shows in general the possibility's.
Many subjects will be discussed in detail in following papers.

In the first releases of Delphi was connecting to a database not possible without the BDE.
The Borland Database Engine is an application which is positioned between the application and the database.
The main goal of the BDE is to establish the connection between the application and the data. The database engine also
deals with the database  transactions.


Through the BDE you can establish a connection on the following manners :

• Direct to local databases like Paradox, dBase, Foxpro, Acces (DAO) and ASCII
• Through ODBC for connecting to vendor clients. (This is slower)
• Through SQL-links you can connect to SQL databases like Interbase, SQL Server etc. (Vendor clients)
  

In a client server environment will the communication be like shown below, starting with the application :

Application  > BDE > SQL Links > Vendor client > TCP/IP -----network----- TCP/IP > RDBMS (Relational DataBaseManagement System)

Besides Delphi offers since version 3 the possibility to skip the BDE.
The component ClientDataSet provides acces through OLE server techniques.

Since version 5 there are two ways (without use of the BDE) solutions :

• ADO (ActiveX Data Objects )
  ADO based applications gets acces to data via a  OLE DB provider.
• Internet Express, special database connection for  web applications via a XML broker.

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