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GK One-Line Question & Answer

15541+ short questions with short answers, covering every category and sub-category on the site — no long articles to scroll through. Good for a fast recap before an exam, or a few minutes of daily practice.

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DBMS → Database Security 3

The tuples of the relations can be of ________ order.
Any
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Choose the correct command to delete an attribute A from a relation R
alter table R drop A
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The UPDATE SQL clause can _____________
update more than one row at a time
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DBMS → PL/SQL 3

Choose the correct statement regarding superkeys
A superkey is an attribute or a group of multiple attributes that can uniquely identify a tuple
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create table apartment(ownerID varchar (5), ownername varchar(25), floor numeric(4,0),<br>primary key (ownerID:));<br>Choose the correct option regarding the above statement
It creates a relation with three attributes ownerID, ownername, floor in which ownerID cannot be null.
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The UNION SQL clause can be used with _____________
SELECT clause only
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DBMS → Introduction to DBMS 3

What is an Instance of a Database?
The state of the database system at any given point of time
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What does the notnull integrity constraint do?
It ensures that all tuples have a finite value on a specified attribute
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Which SQL statement is used to return only different values?
SELECT DISTINCT
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DBMS → Database Architecture 3

What is a foreign key?
A foreign key is an attribute of a relation that is a primary key of another relation
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Which SQL function is used to count the number of rows in a SQL query?
COUNT(*)
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Which SQL keyword is used to sort the result-set?
ORDER BY
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DBMS → Data Models 2

What action does ⋈ operator perform in relational algebra
Output specified attributes from all rows of the input relation and remove duplicate tuples from the output
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Which SQL keyword is used to retrieve a maximum value?
MAX
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DBMS → ER Model 2

What does the “x” operator do in relational algebra?
Output all pairs of rows from the two input relations (regardless of whether or not they have the same values on common attributes)
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Which of the following SQL clauses is used to DELETE tuples from a database table?
DELETE
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DBMS → Relational Model 2

An attribute is a __________ in a relation.
Column
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___________removes all rows from a table without logging the individual row deletions.
TRUNCATE
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DBMS → Normalization 2

What is the method of specifying a primary key in a schema description?
By underlining it using a bold line
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Which of the following is not a DDL command?
UPDATE
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DBMS → Functional Dependency 2

Statement 1: A tuple is a row in a relation Statement 2: Existence of multiple foreign keys in a same relation is possible
Both the statements are true
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Which of the following are TCL commands?
ROLLBACK and SAVEPOINT
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DBMS → SQL Basics 2

Choose the option that correctly explains in words, the function of the following relational algebra expression σyear≥2009 (book ⋈ borrow)
Selects all the tuples from the natural join of book and borrow wherever the year is lesser than 2009
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________________ is not a category of SQL command.
SCL
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DBMS → DDL Commands 2

State true or false: If a relation consists of a foreign key, then it is called a referenced relation of the foreign key dependency.
FALSE
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If you don’t specify ASC or DESC after a SQL ORDER BY clause, the following is used by default ______________
ASC
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DBMS → DML Commands 2

Which of the following information does an SQL DDL not specify?
The operations on the tuples
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Which of the following statement is true?
DELETE does not free the space containing the table and TRUNCATE free the space containing the table
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DBMS → Joins 2

Which of the following data types does the SQL standard not support?
String(n)
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What is the purpose of the SQL AS clause?
The AS SQL clause is used to change the name of a column in the result set or to assign a name to a derived column
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DBMS → Views 2

Which command is used to create a new relation in SQL
create table( , …)
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What does DML stand for?
Data Manipulation language
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DBMS → Indexes 2

If a1, a2, a3 are attributes in a relation and S is another relation, which of the following is an incorrect specification of an integrity constraint?
foreign key(a1, a2)
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With SQL, how do you select all the records from a table named “Persons” where the value of the column “FirstName” ends with an “a”?
SELECT * FROM Persons WHERE FirstName LIKE ‘%a’
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DBMS → Transactions 2

What is the syntax to load data into the database? (Consider D as the database and a, b, c as datA:)
insert into D values (a, b, C:);
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With SQL, how can you return all the records from a table named “Persons” sorted descending by “FirstName”?
SELECT * FROM Persons ORDER BY FirstName DESC
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DBMS → Concurrency Control 2

Which of the following commands do we use to delete a relation (R) from a database?
drop table R
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With SQL, how can you return the number of not null records in the “Persons” table?
SELECT COUNT(*) FROM Persons
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DBMS → Deadlock 2

Which of the following commands do we use to delete all the tuples from a relation (R)?
delete from R
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What does the ALTER TABLE clause do?
The SQL ALTER TABLE clause modifies a table definition by altering, adding, or deleting table columns and/or constraints
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