Microsoft Access

Answer:

All the objects of a database must be protected from unauthorized access, In order to provide protection to the databases created Security for the database must be provided; security prevents intentional and accidental misuse of database. Security is provided by
• Using data encryption and decryption mechanism.
• By providing the authorized users with login credentials.

Answer:

A Sub Query is an Inner query, similar to SQL queries provided by oracle, Access also provides Sub Queries. That is, in a SQL Select query, another Select query is embedded. The second query or the inner query is called as a sub query.
• Sub queries are executed first, the outer query is always evaluated basing on the result of the subquery or inner query.
• For example: user wants to retrieve customers information who are working in department sales.
Select customer_id, customer_name
from tblcustomer
where dept_id = ( Select dept_id from tbldepartment where dept_name='sales');
So here the sub query or inner query "Select dept_id from tbldepartment where dept_name='sales' "is executed first, if suppose the inner query results is one record, that record is used to evaluate the outer query.

Answer:

Multivalued fields are columns in a datasheet whose data value can be selected from a list of values. That is for a field in a record if the user can enter multiple values which can be selected from a list of values available for that particular field.
While creating a multivalued field, when the user selects the value property, all the multiple values available for that field are displayed in separate row.