Question 1 :
The condition in a WHERE clause can refer to only one value.
Question 2 :
The ADD command is used to enter one row of data or to add multiple rows as a result of a query.
Question 3 :
SQL provides the AS keyword, which can be used to assign meaningful column names to the results of queries using the SQL built-in functions.
Question 4 :
The SELECT command, with its various clauses, allows users to query the data contained in the tables and ask many different questions or ad hoc queries.
Question 5 :
A SELECT statement within another SELECT statement and enclosed in square brackets ([...]) is called a subquery.