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Many business problems can be solved using the hardware and software that you currently have on your PC. Modern spreadsheets, databases and word processors are powerful tools that can be customised to suit your needs.

Database management system software serves as an interface between the common database and various application programs. The data definition language defines each data element as it appears in the database before it is translated into the form required by various application programs. The data manipulation language is a special tool for manipulating data in the database. The most prominent data manipulation language is SQL or Standard Query Language, which is the data manipulation language for mainframe database management systems, with versions for microcomputer database management software.

The advantages of database management systems are:

• Data are independent of application programs
• Data redundancy and inconsistency are reduced
• Complexity is reduced by consolidated management of data, access, and use via the DBMS
• Information is easlier to access and use
• The database establishes relationships among different pieces of information
• Data from different records and applications can be more easily accessed and combined.

The 3 database models are:

The Hierarchial Model

This model organizes data in a topdown, treelike manner. Each record is broken down into pieces of records called segments. This model works best for one to many relationships among pieces of data.

This model has well defined access paths. Any piece of data must be accessed from the top downward, starting with the root segment and then going through the subordinate segment.

These models are especially efficient in handling large numbers of data, but are very hard to change data relationships once they have been specified.

The Network Model

This is the best at representing many-to-many relationships. These are more flexible than hierarchical database models but access paths must still be specified in advance. These are also difficult to create new relationships once they have been established without a major programming effort.

The Relational Model

This model was developed to overcome the limitations of the other two models in representing data relationships. This represents all data in the database in simple two dimensional tables called relations. The strength of relational files is that a data element in one file or table can be related to any piece of data in another file or table as long as both tables share a common data element.

When applying database concepts to problem solving, several points must be kept in mind:

1. How the database should be designed.
2. Whether a traditional file access method or a database approach should be chosen
3. If a database approach is appropriate, which database model should be selected.

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