A Query is database object that retrieves specific information from a database.
For example, you can retrieve a student’s name and address from the database.
With Access Queries, you can do the following :
View specific data from Table. Perform calculations on selected records. Delete record from a table. 
You can create new Queries using one of the methods.
Create query in Design View. Create query by using wizard. CREATING A RELATIONSHIP
You need to create the relationship between Tables before you can create Queries.
- See Demonstrations From the CD
Referential Integrity is a set of rules that ensures relationships between Tables within a database are all valid.
CREATING A QUERY IN DESIGN VIEW
- See Demonstrations From the CD
CREATING A QUERY BY USING WIZARD
- See Demonstrations From the CD
TO RUN A QUERY
- See Demonstrations From the CD
EXTENSION : USING PARAMETER
Parameter is a value in a specific field used to retrieve information from the Query such as BioLife in “Brand” field.
Another example, you can type in the date of purchase of vitamin C for the month of August.
Only the information on vitamin C for the month of August which is specified in the perimeter will be displayed.
It is used when searching for a particular piece of information. This enhances the system performance speed.