Nov 29, 2010

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.

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.

11: -What is an EXTENT?
A11: -One or more Oracle datablocks assigned in a contiguous manor to a particular object.

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