SQL Assignments 02

1: -What is Oracle's main character-mode interface?

A1: -SQL*Plus

2: -What is the syntax of the CHANGE command to change text in the SQL buffer?

A2: -C//

3: -The DESCRIBE command is useful for what?

A3: -Displaying Object column names and attributes

4: -What will the command SELECT * FROM EMP do?

A4: -This will show all the rows in the table EMP

5: -In the table EMP, give the ORDER BY clause that will return the rows in the order of DEPTNO ascending and within DEPTNO, SAL descending.

A5: -ORDER BY DEPTNO, SAL desc

6: -What is the difference between a NULL and a 0 field?

A6: -NULL contains no value at all

7: -When using substitution characters (say in an INSERT statement), what is the difference between & and &&?

A7: -& prompts the user for a value with each execution of the SQL statement, && only prompts the user to provide a value on the first SQL statement

8: -What is the difference between the DELETE command and the TRUNCATE command?

A8: -DELETE can selectively delete rows and this command can be undone with a ROLLBACK statement. The TRUNCATE drops all the rows, no selectivity, and the command cannot be reversed

9: -Tablespaces are used for what?

A9: -Tablespaces are storage areas in Oracle, much like a directory structure of a computer. Tablespaces have physical disk drives assigned

10: -Show the syntax to create an index on ename for the table EMP.

A10: -CREATE INDEX ON EMP (ENAME)

11: -What is an EXTENT?

A11: -One or more Oracle datablocks assigned in a contiguous manor to a particular object.