Database Management Systems
Getting Data Together
Database Programs
- A Database Management System (DBMS) is software that helps
you organize data in a way that allows fast and easy access to
the data.
Benefits of a DBMS
- Integrated data - relationships between data
are stored in the program.
- Reduced redundancy - data is stored in just
one place.
- Integrity - file is accurate and up-to-date.
Database Organization
- Hierarchical and network systems are common on mainframes
and minicomputers, while relational systems are more common on
PCs.
- Hierarchical systems are databases in which
some records are subordinate to others.
- Network systems allow subordinate
records to be subordinate to more than one record.
- Relational databases organize data in a table
format consisting of related rows and columns.
Relational DBMS
- A table is also called a relation.
- Each column represents a field, or attribute
.
- All data in any given row is called a record,
or tuple.
File Structure
- There are two steps to creating a database: designing the
structure and entering data.
- Field names are names of the types of data you want.
- Field Types
- Character fields contain descriptive data.
- Numeric fields contain numbers used for calculations.
- Date fields are used for dates.
- Logical fields keep track of true and false conditions.
Additional Database Operations
- Creating a form, or data entry screen for entering
information.
- Listing the records in some desired order, or sorting.
- Running a query to search for a particular record or
list all records that meet some criteria.
- Creating and running a report to output the desired
information.