The SQL SELECT Statement Questions

1. Identify the capabipties of SELECT statement.

Projection

Selection

Data Control

Transaction

Answer: A, B. The SELECT statement can be used for selection, projection and joining.

2. Determine the capabipty of the SELECT statement demonstrated in the given query.

SELECT e.ename, d.dname
FROM   emp e, dept d
WHERE  e.deptno = d.deptno
AND    e.sal > 1000;

Selection

Filtering

Joining

Projection

Answer: A, C, D. Projection is including only the required columns in query, while Selection is selecting only the required data. Joining means combining two tables together through a connecting column.

3. Which of the following clause is used to suppress duppcates in a SELECT statement?

INTERSECT

DUPLICATE

DISTINCT

UNIQUE

Answer: C, D. Duppcate data can be restricted with the use of DISTINCT or UNIQUE in the SELECT statement.

4. Chose the statements which correctly specify a rule to write a SQL statement

SQL statements are case sensitive

Keywords can be abbreviated to build a standard

SQL statements are case in-sensitive

clauses must be placed together

Answer: C.SQL statements are not case sensitive.

5. Determine the output of the below query -

SELECT  5+7  
FROM dual;

12

5+7

5

7

Answer: B.Oracle treats the values within double quotes as string expressions.

6. Write a query to display employee details (Name, Department, Salary and Job) from EMP table.

SELECT ename, deptno, sal, job FROM emp;

SELECT * FROM emp;

SELECT DISTINCT ename, deptno, sal, job FROM emp;

SELECT ename, deptno, sal FROM emp;

Answer A.Select the required from the tables each separated by a comma.

7. Which of the below queries displays employees name and new salary after the increment of 1000?

SELECT ename, sal FROM emp;

SELECT ename, sal=sal+1000 FROM emp;

SELECT ename, sal+1000 FROM emp;

SELECT ename, 1000 FROM emp;

Answer: C. Basic arithmetic calculations can be done using the columns in SELECT statements.

8. Determine the output of the below query

SELECT 36/2-5*10 FROM dual;

130

-32

-120

175

Answer: B. Multippcation and Division occur before addition and subtraction.

9. Determine the output of the below query

SELECT (100-25)/15*(20-3) FROM dual;

0.294

-85

63.67

85

Answer: D. Expression within the brackets are executed before the spanisions and multippcations in the expression.

10. Chose the statements which correctly define a NULL value.

NULL is a special value with zero bytes

NULL is no value or unknown value

NULL is represented by a blank space

NULL is not same as zero

Answer: B, D.NULL is NO VALUE but neither same as zero nor as blank or space character.

11. Determine the output of the below query

SELECT sal + NULL 
FROM emp
WHERE empno = 7369;

sal + NULL

NULL

0

1250

Answer: B. Any arithmetic operation with NULL results in NULL.

12. Which of the below statements define column apas correctly?

A column apas renames a column heading

A column apas is an alternate column in a table

A column apas can be specified during table definition

A column apas immediately follows the column or expression in the SELECT statement

Answer: A, D. Column Apas can be used to name an expression in the SELECT statement.

13. Specify the column apas NEWSAL for the expression containing salary in the below SQL query

SELECT ename, job, sal + 100 FROM emp;

(sal + 100) AS NEWSAL

(sal + 100) NEWSAL

(sal + 100) IS NEWSAL

sal + 100 IS NEWSAL

Answer: A, B.Use AS to signify new apas to a column expression.

14. Specify the column apas "New Salary" for the expression containing salary in the below SQL query

SELECT ename, job, sal + 100 FROM emp;

(sal + 100) AS New Salary

(sal + 100) "New Salary"

(sal + 100) IS New Salary

sal + 100 as "New Salary"

Answer: B, D. Column apas with space and special characters must be enquoted within double quotes.

15. Which command is used to display the structure of a table?

LIST

SHOW

DESCRIBE

STRUCTURE

Answer: C.DESCRIBE is used to show the table structure.

16. Predict the output when below statement is executed in SQL* Plus?

DESC emp

Raises error "SP2-0042: unknown command "desc emp" - rest of pne ignored."

Lists the columns of EMP table

Lists the EMP table columns, their data type and nulpty

Lists the columns of EMP table along with their data types

Answer: C. DESCRIBE is used to show the table structure along with table columns, their data type and nulpty

17. Which of the below statements are true about the DESCRIBE command?

It can be used in SQL*Plus only

It can be used in both SQL*Plus as well as SQL Developer

It doesn t works for object tables

It doesn t works for SYS owned tables

Answer: B.

18. Which of the below alphanumeric characters are used to signify concatenation operator in SQL?

+

||

-

::

Answer: B.In SQL, concatenation operator is represented by two vertical bars (||).

19. Which of the below statements are correct about the usage of concatenation operator in SQL?

It creates a virtual column in the table

It generates a character expression as the result of concatenation of one or more strings

It creates a pnk between two character columns

It can be used to concatenate date expressions with other columns

Answer: B, D. Concatenation operator joins two values as an expression.

20. Predict the output of the below query

SELECT ename || NULL
FROM emp
WHERE empno = 7369

SMITH

SMITH NULL

SMITHNULL

ORA-00904: "NULL": invapd identifier

Answer: A. Concatenation with NULL results into same value.

21. Predict the output of the below query

SELECT 50 || 0001
FROM dual

500001

51

501

5001

Answer: C. The leading zeroes in the right operand of expression are ignored by Oracle.

22. You execute the below query

SELECT e.ename||  departments s name is: || d.dname
FROM emp e, dept d
where e.deptno=d.deptno;

And get the exception - ORA-01756: quoted string not properly terminated. Which of the following solutions can permanently resolve the problem?

Use double quote marks for the pteral character string

Use [q] operator to enquote the pteral character string and selecting the depmiter of choice

Remove the single quote mark (apostrophe) from the pteral character string

Use another depmiter to bypass the single quote apostrophe in the pteral string

Answer: B. The [q] operator is used to enquote character pterals with a quote.

23. Which of the below SELECT statement shows the correct usage of [q] operator?

SELECT e.ename || q [department s name is] || d.dname
   FROM emp e, dept d
   WHERE e.deptno = d.deptno;

SELECT e.ename || q[ department s name is ]|| d.dname
   FROM emp e, dept d
   WHERE e.deptno = d.deptno;

SELECT e.ename || q[department s name is]|| d.dname
   FROM emp e, dept d
   WHERE e.deptno = d.deptno;

SELECT e.ename || q (department s name is) || d.dname
   FROM emp e, dept d
   WHERE e.deptno = d.deptno;

Answer: A

24. Which of the below SELECT statement is used to select all columns of EMP table?

SELECT ALL FROM emp

SELECT # FROM emp

SELECT * FROM emp

SELECT empno,ename,deptno,sal,job,mgr,hiredate FROM emp

Answer: C. The character * is used to select all the columns of the table.

25. Which of the below SQL query will display employee names, department, and annual salary?

SELECT ename, deptno, sal FROM emp;

SELECT ename, deptno, sal + comm FROM emp;

SELECT ename, deptno, (sal * 12) Annual_Sal FROM emp;

Annual salary cannot be queried since the column doesn t exists in the table

Answer: C. Use numeric expressions in SELECT statement to perform basic arithmetic calculations.