1. Which is the subset of SQL commands used to
manipulate Oracle Database structures, including tables?
Data Definition
Language (DDL)
2. What operator performs pattern matching?
LIKE operator
3. What operator tests column for the absence of
data?
IS NULL operator
4. Which command executes the contents of a specified
file?
START <filename> or @<filename>
5. What is the parameter substitution symbol used
with INSERT INTO command?
&
6. Which command displays the SQL command in the SQL
buffer, and then executes it?
RUN
7. What are the wildcards used for pattern matching?
_ for single character substitution and % for
multi-character substitution
8. State true or false. EXISTS, SOME, ANY are
operators in SQL.
True
9. State true or false. !=, <>, ^= all denote
the same operation.
True
10. What are the privileges that can be granted on a
table by a user to others?
Insert,
update, delete, select, references, index, execute, alter, all
11. What command is used to get back the privileges
offered by the GRANT command?
REVOKE
12. Which system tables contain information on
privileges granted and privileges obtained?
USER_TAB_PRIVS_MADE, USER_TAB_PRIVS_RECD
13. Which system table contains information on
constraints on all the tables created?
USER_CONSTRAINTS
14. TRUNCATE TABLE EMP;
DELETE FROM EMP;
Will
the outputs of the above two commands differ?
Both will result in deleting all the rows in
the table EMP.
15. What is the difference between TRUNCATE and DELETE
commands?
TRUNCATE is a DDL command whereas DELETE is a
DML command. Hence DELETE operation can be rolled back, but TRUNCATE operation
cannot be rolled back. WHERE clause can be used with DELETE and not with
TRUNCATE.
16. What command is used to create a table by copying
the structure of another table?
Answer :
CREATE TABLE .. AS SELECT command
Explanation :
To copy only the
structure, the WHERE clause of the SELECT command should contain a FALSE
statement as in the following.
CREATE TABLE
NEWTABLE AS SELECT * FROM EXISTINGTABLE WHERE 1=2;
If the WHERE
condition is true, then all the rows or rows satisfying the condition will be
copied to the new table.
17. What will be the output of the following query?
SELECT
REPLACE(TRANSLATE(LTRIM(RTRIM('!! ATHEN !!','!'), '!'), 'AN',
'**'),'*','TROUBLE') FROM DUAL;
TROUBLETHETROUBLE
18. What will be the output of the following query?
SELECT
DECODE(TRANSLATE('A','1234567890','1111111111'), '1','YES', 'NO' );
Answer :
NO
Explanation :
The query checks
whether a given string is a numerical digit.
19. What does the following query do?
SELECT SAL + NVL(COMM,0) FROM EMP;
This displays the total salary of all
employees. The null values in the commission column will be replaced by 0 and
added to salary.
20. Which date function is used to find the difference
between two dates?
MONTHS_BETWEEN
21. Why does the following command give a compilation
error?
DROP TABLE &TABLE_NAME;
Variable names should start with an alphabet.
Here the table name starts with an '&' symbol.
22. What is the advantage of specifying WITH GRANT
OPTION in the GRANT command?
The privilege receiver can further grant the
privileges he/she has obtained from the owner to any other user.
23. What is the use of the DROP option in the ALTER
TABLE command?
It is used to drop constraints specified on
the table.
24. What is the value of ‘comm’ and ‘sal’ after
executing the following query if the initial value of ‘sal’ is 10000?
UPDATE EMP SET SAL = SAL + 1000, COMM = SAL*0.1;
sal = 11000, comm = 1000
25. What is the use of DESC in SQL?
Answer :
DESC has two purposes. It is used to describe
a schema as well as to retrieve rows from table in descending order.
Explanation :
The query SELECT
* FROM EMP ORDER BY ENAME DESC will display the output sorted on ENAME in
descending order.
26. What is the use of CASCADE CONSTRAINTS?
When this clause is used with the DROP
command, a parent table can be dropped even when a child table exists.
27. Which function is used to find the largest integer
less than or equal to a specific value?
FLOOR
28. What is the output of the following query?
SELECT TRUNC(1234.5678,-2) FROM DUAL;
1200