Database servers

What is Database server?

A database server is a computer program that provides database services to other computer programs or computers, as defined by the client-server model. The term may also refer to a computer dedicated to running such a program. Database management systems frequently provide database server functionality, and some DBMSs (e.g., MySQL) rely exclusively on the client-server model for database access.

Types of databases

1. Flat file

A flat file database is a simple text file used to store information. Within such a record, the single fields can be separated by delimiters, e.g. commas, or have a fixed length. In the latter case, padding may be needed to achieve this length. Extra formatting may be needed to avoid delimiter collision. There are no structural relationships between the records. Flat file database is most often used when you do not have access to a MySQL database, as they require no server addons other than PHP. They are best for smaller amounts of data than a MySQL database is capable of, and have fewer handling functions.

2. Relational DBMS

A relational database management system (RDBMS) is a database management system (DBMS) that is based on the relational model. This adds the additional condition that the system supports a tabular structure for the data, with enforced relationships between the tables. This excludes the databases that don't support a tabular structure or don't enforce relationships between tables.
Benefits of RDBMS are that the system is simple, flexible, and productive. Because the tables are simple, data is easier to understand and communicate with others. RDBMS are flexible because users do not have to use predefined keys to input information. Also, RDBMS are more productive because SQL is easier to learn. This allows users to spend more time inputting instead of learning. More importantly, RDBMS’s biggest advantage is the ease with which users can create and access data and extend it if needed. After the original database is created, new data categories can be added without the existing application being changed.

3. Object- oriented DBMS(OODBMS)

An object-oriented database management system (OODBMS) is a database management system (DBMS) that supports the modeling and creation of data as objects. This includes some kind of support for classes of objects and the inheritance of class properties and methods by subclasses and their objects. An object-oriented database system must satisfy two criteria: it should be a DBMS, and it should be an object-oriented system, i.e., to the extent possible, it should be consistent with the current crop of object-oriented programming languages. The first criterion translates into five features: persistence, secondary storage management, concurrency, recovery and an ad hoc query facility. The second one translates into eight features: complex objects, object identity, encapsulation, types or classes, inheritance, overriding combined with late binding, extensibility and computational completeness.


2 and 3 tier database

The 2-tier database model is a standalone application with data tightly bound (mainframe systems and workgroup database systems). In modern two-tier architecture, the server holds both the application and the data. The application resides on the server rather than the client, probably because the server will have more processing power and disk space than the PC.

The 3-tier model is more popular for business where the database backend is an Enterprise Relational Database such as Sybase or Oracle, with generally no direct access to the database. In three-tier architecture, the data and applications are split onto separate servers, with the server-side distributed between a database server and an application server. The client is a front end, simply requesting and displaying data. Reason being that each server will be dedicated to processing either data or application requests, hence a more manageable system and less contention for resources will occur