CUET CS Chapter-Structured Query Language(SQL) 

MCQ-Based Questions for CUET Computer Science Chapter-Structured Query Language(SQL) 

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Practice Questions for CUET Computer Science chapter-Structured Query Language(SQL) SET-1

Computer Science - MCQ on Structured Query Language

Class XII

Q.1 The function, which returns specific portion of a string, is

a) SUBSTR

b) SUBSTRING

c) INSTR

d) STRING

Answer:

(a)

Explanation: The function, which returns substring of a string, is SUBSTR.

Q.2 If, I create an object without a TABLESPACE clause, then Oracle stores the segment in

where will Oracle store the segment.

a) it will give an error.

b) system tablespace.

c) users tablespace.

d) default tablespace.

Ans d)

Explanation: All the objects without a tablespace clause are stored in Default tablespace.

Q.3 The character, which is used to continue a statement in SQL* PLUS, is

a) *

b) /

c) –

d) @

Answer:

(c)

Explanation: – is used to continue statements in SQL* plus.

Q.4 Assuming today is Monday, 10 July 2000, this is returned by this statement: SELECT to_char(NEXT_DAY(sysdate, 'MONDAY'), 'DD-MON-RR') FROM dual

a) 03 JUL 00.

b) 10 JUL 00.

c) 12 JUL 00.

d) 17 JUL 00.

Answer:

(d)

Explanation: NEXT_DAY returns the date of the next weekday specified in the 2nd argument.

Q.5 The command, which is used to extract data from database, is

a) SELECT.

b) GET.

c) OPEN.

d) READ.

Answer:

(a)

Explanation: SELECT command is used to select or extract data from database table.

Q.6 The sql statement, wich is used to insert new data in the database, is

a) ADD RECORD.

b) ADD NEW.

c) INSERT.

d) INSERT NEW.

Answer:

(c)

Explanation: INSERT command is used to insert values in the database.

Q.7 The sql statement, which is used to delete particular data in the database, is

a) DELETE.

b) DROP.

c) TRUNCATE.

d) REMOVE.

Answer:

(a)

Explanation: The SQL TRUNCATE TABLE clause deletes all rows from a database table. We use truncate command only when we want to delete all rows in a table.

Q.8 The correct sql query if I want to change "Hansen" into "Nilsen" in the "LastName" column in the Persons table is

a) UPDATE Persons SET LastName='Nilsen' WHERE LastName='Hansen'.

b) MODIFY Persons SET LastName='Hansen' INTO LastName='Nilsen.

c) UPDATE Persons SET LastName='Hansen' INTO LastName='Nilsen'.

d) MODIFY Persons SET LastName='Nilsen' WHERE LastName='Hansen'.

Answer:

(a)

Explanation: When we need to change some values in an existing row we can use update command. It specifies the rows to be changed using the where clause.

Q.9 The statement, which is used to update data in the database, is

a) SAVE AS.

b) UPDATE.

c) SAVE.

d) MODIFY.

Answer:

(b)

Explanation: UPDATE is used to change some values in an existing row command. It specifies the rows to be changed using the where clause.

Q.10 The proper syntax of CREATE TABLE command is

a) CREATE TABLE <table-name> (<datatype>[(size)],<data type> <size>);

b) Create <tablename> <datatype > <size>,<column name><datatype > <size>;

c) CREATE TABLE <tablename> (<column name1 ,<datatype>[<size>]),<column name2 >, datatype>[<size>]..).

d) CREATE <table-name> (<datatype>[(size)],<data type> <size>);

Answer:

(c)

Explanation: When a table is created its column names, data types and size are supplied for each column.

Q.11 A constraint is

a) a command in the SQL *plus.

b) the conditions or checks on table only .

c) the conditions or checks on columns of a table only.

d) the condition or check on one or more columns of a table.

Answer:

(d)

Explanation: A constraint is a condition or check applicable on a field or set of fields. Two basic types of constraints are column constraints and table constraints.

Q.12 NOT NULL constraint ensure that

a) a column can never have empty values.

b) a column cannot have value 0.

c) a column can have empty value.

d) a column can have value 0.

Answer:

(a)

Explanation: NOT NULL constraint ensure that we cannot leave the column blank or empty and must provide a value to it, where zero or greater than it.

Q.13 UNIQUE constraint ensure that

a) two rows can have same value in the specified column.

b) no two rows can have same value in the specified column.

c) data delicacy can be there.

d) data inconsistency may /may not be there.

Answer:

(a)

Explanation: It ensures the value in a column is unique. It can be applied to one or more columns.

Q.14 In primary key constraints,

a) the primary key can have null value.

b) same as unique constraint.

c) declares column as the primary key and cannot have null value.

d) declares column as the primary key and can have null value.

Answer:

(c)

Explanation: Primary key constraint declares the column, as primary key of the table can primary key cannot have null values. It can be applied to one or more columns.

Q.15 If, I want to select all columns from a table named CLASS, then the correct method, is

a) SELECT * FROM CLASS.

b) SELECT (ALL) FROM CLASS.

c) SELECT CLASS.

d) SELECT *. FROM CLASS.

Answer:

(a)

Explanation: Data is selected from the table using SELECT command.

Q.16 If, I want to select one column named Marks from a table having duplicate rows named Student, then the correct method, is

a) SELECT Marks FROM Student;

b) SELECT DISTINCT Marks from Student;

c) SELECT Marks. Student;

d) SELECT Student “Marks”;

Answer:

(a)

Explanation: DISTINCT eliminates the duplicate rows from the result of SELECT statement.

Q.17 If, I want to create the Customer table specified as Customer (First Name, Last Name, Address, City, Country, Birth Date), then the SQL command, will be

a) CREATE TABLE Customer (First_Name ,Last_Name ,Address ,City,Country char, Birth_Date );

b) CREATE TABLE Customer (First_Name char(25 Last_Name char(25,Address char(50, City char(25,Country char(25,Birth_Date date );

c) CREATE TABLE Customer (First_Name char(25 Last_Name char(25,Address char(50, City char(25,Country char(25,Birth_Date date (21 );

d) CREATE TABLE Customer (First_Name char(25 ||” “|| Last_Name char(25 || “ “ || Address char(50 || “ “|| City char(25 || “ “||Country char(25||” “|| , Birth_Date date “ ADDRESS” );

Answer:

(b)

Explanation: || is concatenation operator and only one column will be displayed as “ADDRESS” and the syntax of date is date. It cannot hold size of (21. It is yyyy-mm-dd.

Q.18 Aggregate functions are

a) Avg, min, max, sum and count.

b) Select, update, delete.

c) Avg, sum, create and update.

d) Min, Max, Order By, Group By.

Answer:

(a)

Explanation: Aggregate functions operate on a aggregate of tuples. These are max, min, avg, sum, stddev, count, variance etc. The result of aggregate functions is a single value.

Q.19 If, I want to select all the records from a table named STUDENTS where First Name is “Aditi” and Last name is “Suneja”, then the sql command, will be

a) SELECT First Name =’Aditi’, Last Name=’Suneja’.

b) SELECT * From STUDENT where First Name =’Aditi’ OR Last Name=’Suneja’.

c) SELECT * From STUDENT where First Name =’Aditi’ AND Last Name=’Suneja’.

d) SELECT * From STUDENT where First Name LIKE ’Aditi’ AND Last Name LIKE ‘Suneja’.

Answer:

(c)

Explanation: AND operator displays a record when all the conditions are met where as OR operator displays the record if any of the condition is met.

Q.20 If, I want to select all the records from a table named "STUDENTS" where the "FIRST NAME" is alphabetically between (and including) "Aditi" and "Mukta", then the sql command, will be

a) SELECT * FROM STUDENTS WHERE First Name>'Aditi” AND First Name<’Mukta’

b) SELECT * FROM STUDENTS WHERE First Name BETWEEN 'Aditi' AND ‘Mukta’

c) SELECT First Name>'Aditi AND First Name< ‘Mukta’ FROM STUDENTS.

d) SELECT (all) FROM STUDENTS WHERE First Name IS 'Aditi' AND ‘Mukta’

Answer:

(b)

Explanation: Between operator includes the name “Aditi” and “Mukta” also. > and < operators does not include these two names.

Practice Questions for CUET Computer Science chapter-Structured Query Language(SQL) SET-2

Q.21 The problem with navigational data access languages was

a) the user had to have knowledge of the table and index structures.

b) navigational data access was far slower than declarative access.

c) navigational access languages required the coder to embed their queries inside a procedural language shell.

d) navigational languages were far slower then SQL.

Answer:

(a)

Explanation: A navigational data language requires knowledge of the internal tables and index structures.

Q.22 The major problem with SQL is

a) SQL cannot support object-orientation.

b) the same query can be written in many ways, each with vastly different execution plans.

c) SQL syntax is too difficult for non-computer professionals to use.

d) SQL creates excessive locks within the Oracle database.

Answer:

(b)

Explanation: The declarative nature of SQL makes it possible to write an individual query in many different forms, each with identical results. For example, a query can be written with a standard join, a non-correlated sub-query or a correlated sub-query, each producing identical results but with widely varying internal execution plans.

Q.23 The important feature of relational databases and SQL is

a) independence of table relationship.

b) high speed of SQL.

c) powerful GUI front-end.

d) easy to install and use.

Answer:

(a)

Explanation: Prior to the invention of relational databases, it was very difficult to establish relationships with other database objects and systems relied on pointers in order to establish data relationships. With the advent of relational database management, it became possible to establish ad-hoc relationships using SQL joins.

Q.24 The important consideration when tuning an SQL statement is

a) the number of CPUs on the server.

b) the degree of parallelism on the tables.

c) the use of bitmap indexes.

d) the quality of the SQL optimization.

Answer:

(d)

Explanation: SQL coder need not be concerned with the proper work of joining the tables together.

Q.25 The database design feature, which is most important to SQL performance, is

a) removal of data redundancy.

b) the introduction of data redundancy.

c) the introduction of non-first normal form relations.

d) the introduction of SQL*Plus.

Answer:

(b)

Explanation: The degree of normalization in the database design is critical to SQL performance. The ideal candidates for the introduction of redundancy are small data items that are updated very infrequently.

Q.26 The relationship between indexes and SQL performance is that

a) indexes are only used in special cases.

b) indexes are used to make table storage more efficient.

c) indexes rarely make a difference in SQL performance.

d) indexes exist solely to improve query speed.

Answer:

(d)

Explanation: The sole purpose of indexes in any relational database management system is to reduce the access time for SQL statements. If, indexes did not exist in a relational database, then the Oracle database SQL optimizer would have no choice except to read every single row.

Q.27 The number of columns that are presented after executing this query SELECT address1||','||address2||','||address3 "Address" FROM employee are

a) 1.

b) 2.

c) 3.

d) 0.

Answer:

(a)

Explanation: Only one column appears as || is the concatenation operator.

Q.28 The Oracle access method, which is the fastest way for Oracle to retrieve a single row, is

a) primary key access.

b) access through unique index.

c) table access by ROWID.

d) full table scan.

Answer:

(c)

Explanation: Table access by Rowid is the fastest access method.

Q.29 The valid column name is

a) column.

b) 1966_invoice.

c) Catch_#22.

d) #invoices.

Answer:

(c)

Explanation: A column name cannot start with a digit or hash. A column is a reserved word; it is possible only if it would have been inside quotes like “column”.

Q.30 The command, which will delete all data from a table and will not write to the rollback segment, is

a) DROP.

b) DELETE.

c) CASCADE.

d) TRUNCATE.

Answer:

(d)

Explanation: The truncate command does not write data to the user segment.

Q.31 The sql statement, which will return only different values, duplicate values will be deleted in select statement, is

a) SELECT DIFFERENT.

b) SELECT UNIQUE.

c) SELECT NOT NULL.

d) SELECT DISTINCT.

Answer:

(d)

Explanation: DISTINCT removes duplicate values.

Q.32 The SQL keyword, which is used in ascending or descending i.e. sorting the result set, is

a) ORDER BY.

b) HAVING.

c) GROUP BY.

d) SORT.

Answer:

(a)

Explanation: ORDER BY is used for sorting the result set. By default it will sort in ascending order but if, we want the result set in descending order, then we use ORDER BY DESC.

Q.33 The SELECT statement used in a view definition can not include

a) INSERT.

b) UPDATE.

c) DELETE.

d) ORDER BY.

Answer:

(d)

Explanation: A view is a virtual table with no data, but can be operated like any other table.

Q.34 If, I want to change Roll No 400 only for those items that have Roll No 300, then the sql statement, will be

a) MODIFY items SET Roll No=400 Where Roll N = 300;

b) UPDATE items SET Roll No=400 Where Roll N = 300;

c) UPDATE items Roll No=400 in place of Roll N = 300;

d) UPDATE items Roll No=400 HAVING Roll N = 300;

Answer:

(b)

Explanation: UPDATE command is used when we want to change the values of some specified columns and it is used with WHERE clause.

Q.35 If, I want to update roll no to 300 and marks to 100 of students having icode <I040, then the sql statement, will be

a) UPDATE items SET Roll No=400; Marks = 100 Where Icode<I040;

b) UPDATE items SET Roll No=400, Marks = 100 Where Icode<I040;

c) UPDATE items SET Roll No=400 And SET Marks = 100 Where Icode<I040

d) UPDATE items SET Roll No=400, Marks = 100 Where Icode>I040

Answer:

(b)

Explanation: To update multiple columns, multiple column assignments can be specified with SET clause, separated by commas.

Q.36 If, I want to create a view named as “ taxpayee” having details of employees from EMPLOYEE Table that have gross more, than 8000 then the sql statement, will be

a) CREATE VIEW taxpayee AS SELECT * FROM EMPLOYEE WHERE gross >8000;

b) SELECT VIEW taxpayee AS SELECT * FROM EMPLOYEE WHERE gross >8000;

c) CREATE VIEW taxpayee AND SELECT * FROM EMPLOYEE WHERE gross >8000;

d) SELECT VIEW taxpayee FROM EMPLOYEE WHERE gross >8000;

Answer:

(a)

Explanation: We can create view using CREATE VIEW, the name of the view to be created, the word AS, and then the query.

Q.37 A view is

a) a table where we can see information.

b) a table which exists.

c) a table which does not exists physically but it is like a window where we can view or change information in a table.

d) a virtual table which contains copy of the data.

Answer:

(c)

Explanation: A view only stores its definition. Its data is derived from base table.

Q.38 Various built in functions provided in SQL are

a) LOWER, UPPER and REPLICATE.

b) ALTER AND DROP.

c) SELECT, CREATE.

d) UPDATE.

Answer:

(a)

Explanation: SQL provides several types of built in functions that return different kinds of information from the database. These are lower, upper, replicate, substr, getdate()etc. SELECT, UPDATE, ALTER, DROP are commands in SQl.

Q.39 A view

a) cannot be updatable.

b) is updatable always.

c) may or may not be updatable.

d) does not exists in SQL.

Answer:

(c)

Explanation: We can use update commands (INSERT, DELETE, UPDATE) on updatable views. A view is updatable if, it has been defined from a single relation and the update query can be mapped on to the base table successfully.

Q.40 If, I have a table EMPLOYEE (ecode,ename,sex,egrade,egross) in which e code is the primary key and I create a view

Create view sample

AS SELECT ename, gross

FROM employee;

And use the following command

INSERT INTO sample

Values (‘aditi’,5000.00;

, then

a) it will insert values.

b) the last two statements can not be mapped on to base table employee.

c) insert command cannot be used.

d) instead of Insert, Update command to be used.

Answer:

(b)

Explanation: The last two statements can not be mapped on to base table employee as the value of the primary code e code is missing and also the sex column does not have any default value and it cannot have null at the same time. Thus this view is not updatable.

Q.41 The function of the following sql statement is

SELECT replicate (“*”,5 ) FROM Names;

a) it will return *5.

b) it will return **55.

c) it will return *****.

d) it will return 55.

Answer:

(c)

Explanation: It repeats the given expression the specified number of times.

Q.42 The function of the following sql statement is

SELECT substr (“Aditi”, 3,3 ) FROM Names;

a) it will return iti.

b) it will return i.

c) it will return Adi.

d) it will return iti iti iti.

Answer:

(a)

Explanation: Substr (expn, start position, no of char) returns the given no of chars (integer) from a character string expn starting at the specified startpos (integer).

Q.43 The function of the following sql statement is

SELECT getdate() FROM Names;

a) this function does not exists.

b) it will return the current system date.

c) it will return the previous day system date.

d) it will return the following day system date.

Answer:

(b)

Explanation: This function returns the current system date of your computer.

Q.44 When I drop a table and then use the select statement to access its dependent view, it will result

a) in creating the view.

b) in an error.

c) in showing the view table which had been created.

d) in showing the base table which was dropped.

Answer:

(b)

Explanation: As the table is dropped that means it has been deleted from database so its dependent view will not generate any table and give an error.

Q.45 DROP table command in sql lets you drop a table

a) if it has rows.

b) if it is not an empty table.

c) it may or may not be an empty table.

d) only if it is an empty table.

Answer:

(d)

Explanation: A table with rows in it cannot be dropped. First we use a DELETE command to remove all the rows then we can drop the empty table so that it is no longer recognized in the database.

Q.46 To delete a view from database when view is called names and base table employee we use the command

a) DROP VIEW names.

b) DELETE VIEW names.

c) DROP VIEW employee.

d) DROP VIEW.

Answer:

(a)

Explanation: DROP command deletes a view from database. Its syntax is DROP VIEW (viewname).

Q.47 If, I use command DROP VIEW names, then

a) only view names will be deleted from database.

b) view names as well as its base table will be deleted from data base.

c) only base table will be deleted.

d) either view name or base table will be deleted from database.

Answer:

(a)

Explanation: When a view is dropped, only view is deleted. It does not cause any change in the base table and the base table remains intact.

Q.48 To remove the tuples from an employee table where salary >5000 the sql query is

a) DELETE FROM table named employee WHERE salary >5000;

b) DELETE employee WHERE salary >5000;

c) DELETE FROM employee WHERE salary >5000;

d) DELETE employee having salary>5000;

Answer:

(c)

Explanation: Delete command is used to remove some or all of the rows in a table.

Q.49 To remove all the tuples from an employee table the sql query is

a) DELETE FROM employee;

b) DELETE ALL FROM employee;

c) DELETE * FROM employee;

d) DELETE employee;

Answer:

(a)

Explanation: DELETE <tablename> will delete all the rows in a table and table would be empty.S

Q.50 To insert values in the tablename students (name, roll no, sex, grade, salary) the sql query would be

a) INSERT INTO students VALUES (2,’aditi’, ‘f’,’e1’, 10,000;

b) INSERT INTO students VALUES (2,’aditi’, ‘e1,’f’, 10,000;

c) INSERT INTO students VALUES (‘aditi’, 20,‘f’,’e1’, 10,000;

d) INSERT INTO (name, roll no, sex, grade, salary) VALUES (‘aditi’, ‘20’,‘f’,’e1’, 10,000;

Answer:

(c)

Explanation: To insert values either of these commands can be used. INSERT INTO students VALUES (‘aditi’, ‘20’,‘f’,’e1’, 10,000; or INSERT INTO students (name, roll no, sex, grade, salary) VALUES (‘aditi’, ‘20’,‘f’,’e1’, 10,000;. The data values order should match with the table columns when we create table.

Q.51 If, I want to insert only name and roll no, then I use the command

INSERT INTO students VALUES (‘aditi’, 20; the columns that are not listed

a) will have 0 value.

b) will have null value always.

c) will have default value always.

d) will have default value if it is defined otherwise Null value.

Answer:

(d)

Explanation: In an INSERT statement, only those columns can be omitted that have either default value defined or they allow null values.

Q.52 If, I want to select the rows from students table whose salary >2000 and place them in the employee table, then the sql query would be

a) INSERT INTO employee SELECT * FROM student WHERE salary >2000;

b) INSERT INTO employee SELECT * FROM students WHERE salary >2000;

c) INSERT INTO students SELECT * FROM employee WHERE salary >2000;

d) INSERT INTO employee SELECT * FROM student HAVING salary >2000;

Answer:

(b)

Explanation: We will simply replace the VALUES clause with the sql query selecting the rows from the employee table.

Q.53 ALTER TABLE command

a) add columns in a table only.

b) modify the column size only.

c) delete some columns in a table only.

d) can either add columns, modify the sizes or delete columns in a table.

Answer:

(d)

Explanation: ALTER table command is used to change the definitions of existing tables. IT can modify, delete or change sizes of columns.

Q.54 If, I want to calculate the total salary for employees grade ‘A1’, then the sql query would be

a) SELECT total (salary) FROM employee WHERE grade=’A1’;

b) SELECT sum (salary) FROM employee WHERE grade=”A1”;

c) SELECT sum (salary) FROM employee WHERE grade=’A1’;

d) SELECT sum (salary) FROM employee HAVING (grade) =”A1”;

Answer:

(c)

Explanation: Sum is used to calculate the total salary.

Q.55 To display the average salary of employees with grades ‘E2’ or ‘E4’, the sql command is

a) SELECT avg(salary) FROM employee WHERE (grade=’E2’ OR grade=’E4’);

b) SELECT avg(salary WHERE (grade=’E2’ OR grade=’E4’);

c) DISPLAY avg(salary) FROM employee WHERE (grade=’E2’ OR grade=’E4’);

d) SELECT avg(salary) FROM employee HAVING (grade=’E2’ AND grade=’E4’);

Answer:

(a)

Explanation: AVERAGE is an aggregate function used in SQL and is used with WHERE clause.

Q.56 To count the number of employees in employee table, the sql command is

a) SELECT count (*) FROM employee;

b) SELECT count (*) employee;

c) SELECT * FROM employee;

d) SELECT count FROM employee;

Answer:

(a)

Explanation: COUNT is also an aggregate function used in SQL.

Q.57 To count the number of cities, the different members belong to in employee table, the sql command is

a) SELECT count (DISTINCT) FROM employee;

b) SELECT count (DISTINCT city) FROM employee;

c) SELECT count (ALL city) FROM employee;

d) SELECT count (DISTINCT city);

Answer:

(b)

Explanation: DISTINCT keyword ensures that the multiple entries of the same city are ignored.

Q.58 To count the number of non null cities, the different members belong to in employee table, the sql command is

a) SELECT count (ALL city) FROM employee;

b) SELECT count (DISTINCT) FROM employee;

c) SELECT count (ALL) FROM employee;

d) SELECT count (DISTINCT city) FROM employee;

Answer:

(a)

Explanation: As we want to count the entries including repeating entries for the city we have to use keyword ALL. The * is the only argument that includes null when it is used only with COUNT.

Q.59 The subdivision of SQL, which is used to put values in tables, is

a) DDL.

b) DDL AND DML.

c) DML.

d) DNL.

Answer:

(c)

Explanation: Data Manipulation Language (DML) provides statements to enter, update, delete data and perform complex queries on these tables.

Q.60 The subdivision of SQL, which is used to create tables, is

a) DDL.

b) DDL AND DML

c) DML

d) DDL or DML

Answer:

(a)

Explanation: Data Definition Language (DDL) provides statements for creation and deletion of tables and indexes.