quiz 1

TCL stands for Transaction Control Commands used for managing the changes made by DML commands like INSERT, DELETE, and UPDATE. The TCL commands are automatically committed in the database; that's why we cannot use them directly while creating tables or dropping them.

The iteration structure is obtained by the use of loop constructs.

AVG is an aggregate function in SQL. It returns average value after calculating from values in a numeric column.

IS NULL operator is used to look for null values.

A superkey with no redundant attribute is known as candidate key. Hence , option (1) is correct.

TRUNCATE statement delete all rows in a table without having the action logged.

In SQL modify command is used to modify records in DB table.

DISTINCT keyword is used to SELECT only one copy of each set of duplicate rows.

The CURRVAL returns the current value of the sequence.

A view is also known as a virtual table because it contains rows and columns similar to a real table. It shows the table interface but cannot be stored in a database.