What is the difference between logical standby database and physical stand by database?

Why do you need to have data guard?

What is data guard?

What are the services required on primary database?

Is there any difference in the data changes in primary and secondary database?

What is the maximum number of standby database that can be associated with a production database?

Explain the architecture of data guard?

What happens when stand by database is not available?

How can you find out whether a database is primary or standby?

Which class is used for converting the data types?

What is the difference between dynamic and var data types?