Skip to main content

Question 6: ORDER BY with NULL

You are sorting data in a table in you SELECT statement in descending order.
The column you are sorting on contains NULL records, where will the NULL record appears?

A.At the beginning of the list.

B.At the end of the list.

C.In the middle of the list.

D.At the same location they are listed in the unordered table.


Answer: A


Explanation:
When sorting a column with null values in ascending order then the oracle places the Null values
at the end of the list if the sorting is in descending order the oracle places the null values at the
start of the list.

Comments

Popular posts from this blog

Question 8: Aggregate Functions

Examine the description of the STUDENTS table: STD_ID NUMBER(4) COURSE_ID VARCHARD2(10) START_DATE DATE END_DATE DATE Which two aggregate functions are valid on the START_DATE column? (Choose two) A. SUM(start_date) B. AVG(start_date) C. COUNT(start_date) D. AVG(start_date, end_date) E. MIN(start_date) F. MAXIMUM(start_date) Answer: C & E Explanation: It is possible to apply COUNT() and MIN() functions on the column with DATE data type. Incorrect Answers A: Function SUM() cannot be used with DATE data type column. B: Function AVG() cannot be used with DATE data type column. D: Function AVG() cannot be used with DATE data type column, and function AVG() just has one parameter X, not two. It averages all X column values returned by the SELECT statement. F: There is no MAXIMUM() function in Oracle, only MAX() function exists.

20. TRIM Function

Which SELECT statement will the result 'elloworld' from the string 'HelloWorld'? A. SELECT SUBSTR( 'HelloWorld',1) FROM dual; B. SELECT INITCAP(TRIM ('HelloWorld', 1,1)) FROM dual; C. SELECT LOWER(SUBSTR('HellowWorld', 1, 1) FROM dual; D. SELECT LOWER(SUBSTR('HelloWorld', 2, 1) FROM dual; E. SELECT LOWER(TRIM ('H' FROM 'HelloWorld')) FROM dual; Answer: E Explanation: TRIM function accept a string describing the data you would like to trim from a column value. It can trim from both side of column value i.e. left and right. In the following statement this functionwill trim as SELECT LOWER(TRIM ('+' FROM 'HelloWorld')) FROM dual; From the above statement trim function will remove the character 'H' from 'HelloWorld' and LOWER function will convert the remaining character to lower case.