- Relationship between two sets of entities A and B is many-to-many when
o For each entity in A, there can be many related entities in the B, and
o For each entity in B, there can be many related entities in A.
- For example, many students can read many subjects
- A table consists of rows and columns.
- Within a table, data is stored as records.
- A database may contain one or more tables.
- Each row in a table represents one record.
- Column is called “Field” and row is called “Record” in database.
- Query is the request to extract data from database.
- It consists of a command that is given to display data.
- The results of a query are in the form of a table.
- Main Advantages of using queries are
- o Extract particular records from one or more tables without modification of the actual data.
- o Sort records in a particular data
- o Display the selected records on the screen; print them on the printer, etc.
- Form is a window that collects data from a database and organizes it on the computer screen.
- It is used to
o Retrieve data from the database and display it. o Enter data into the database.
o Edit data in the database.
- Forms are designed to make data entry and retrieval easier.
- Forms provide a user friendly interface. So non-technical user can work easily.
- A form usually displays only one record at a time so it is easier to edit and enter data by using form.
- A form can collect and display data from more than one table.
- Presentation of selected data retrieved from a database in a predefined manner is called a Report.
Presentation of data in formatted form.
Presentation of processed data obtained from a database is called Report.
- Report can be displayed on the screen, printed on the paper or stored on the disk.
- It can retrieve data from one or more tables of a database.
DIFFERENCE BETWEEN FORMS & REPORTS: