Which of the following is not a possible meaning of the SQL marker NULL?

Given the following schema, Pet (petId: integer, petType: string, petName: String, favoriteFood: String) Cat (petId: integer (FK), furColor: string) Dog (petId: integer (FK), furColor: string) Bird (petId: integer (FK), canFly: boolean)   Which relational algebra expression is going to produce a list of distinct bird names for the birds who can fly?

In respect to Transaction ACID properties, Atomic property stands for the fact that  

INSERT SQL statement can be used to do the following:

As discussed in this class, the JDBC automatically closes connection when not used by the application

Which of the following SQL clauses are required in any SQL SELECT query and cannot be omitted?

SQL would never allow you to execute a join on a table with itself.

Given the following SQL query:          SELECT *FROM EMP WHERE LName = “Smith” AND Salary < 10000 What indexing method is the best to use for Salary field?

A relation with only simple (non-compound) keys will already be in 2NF if it also in 1NF.

What is data granularity of a DB?