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Worksheetstest1
Total questions: 28
Worksheet time: 18mins
What is the result?
SELECT COUNT(DISTINCT dept_id) FROM emp;
A. Total employees
B. Total departments
C. Duplicate departments
D. NULL
Which data type stores large text?
A. CHAR
B. VARCHAR
C. TEXT
D. BOOLEAN
What will this return?
SELECT * FROM emp WHERE salary != 50000;
A. All salaries except 50000
B. Only 50000
C. Error
D. NULL rows
SELECT * FROM emp e LEFT JOIN dept d
ON e.dept_id = d.dept_id;
A) Only matching rows
B) All emp rows
C) All dept rows
D) Error
DELETE FROM emp;
ROLLBACK;
A) Data restored
B) Data lost
C) Error
D) Partial restore
Which statement is WRONG?
A) DELETE can use WHERE clause
B) TRUNCATE removes table structure
C) DROP deletes table permanently
D) DELETE can be rolled back
Which statement is INCORRECT?
A) AVG() ignores NULL values
B) COUNT(column) counts NULL values
C) SUM() ignores NULL values
D) MAX() ignores NULL values
To check NULL values in MySQL, we use:
A) = NULL
B) != NULL
C) IS NULL
D) == NULL
SELECT * FROM emp ORDER BY salary;
A) Sorted ascending
B) Sorted descending
C) Random order
D) Error
What is the effect of this query?
DELETE FROM emp WHERE dept_id IS NULL;
A) Deletes all rows
B) Deletes rows with NULL dept_id
C) Deletes table
D) Error
Table emp has 100 rows.
10 rows have salary = NULL.
What is the result of:
SELECT COUNT(salary) FROM emp;
A) 100
B) 90
C) 10
D) NULL
Table emp has salaries:
5000, 7000, NULL, 9000, NULL
SELECT AVG(salary) FROM emp;
A) 7000
B) 5250
C) 6200
D) NULL
Table emp has salaries:
1000, 2000, 3000, 4000
SELECT MAX(salary) - MIN(salary) FROM emp;
A) 3000
B) 4000
C) 1000
D) Error
Table emp has multiple departments.
SELECT dept_id FROM emp GROUP BY dept_id HAVING COUNT(*) = 1;
This returns:
A) All departments
B) Departments with single employee
C) Departments with multiple employees
D) Error
SELECT DATEDIFF('2024-03-10','2024-03-01');
A) 9
B) 10
C) -9
D) Error
SELECT *
FROM emp
WHERE salary > ANY (SELECT salary FROM emp WHERE dept_id = 10);
Returns:
A) Employees earning more than all in dept 10
B) Employees earning more than at least one in dept 10
C) Employees of dept 10
D) Error
How many layers are there in the OSI model?
A) 5
B) 6
C) 7
D) 8
Which layer of the OSI model is responsible for encryption and compression?
A) Session
B) Presentation
C) Application
D) Transport
Which OSI layer provides end-to-end communication?
A) Network
B) Transport
C) Session
D) Data Link
Which device operates at the Network layer?
A) Hub
B) Switch
C) Router
D) Repeater
How many bits are there in an IPv4 address?
A) 16
B) 32
C) 48
D) 64
Which IP address is used for loopback?
A) 192.168.1.1
B) 127.0.0.1
C) 0.0.0.0
D) 255.255.255.255
Which transmission mode supports two-way simultaneous communication?
A) Simplex
B) Half-duplex
C) Full-duplex
D) Broadcast
A = [2, 4, 6, 8]
sum = 0
FOR i = 0 TO length(A)-1
sum = sum + A[i]
END FOR
PRINT sum
A) 12
B) 14
C) 18
D) 20
QUEUE Q
ENQUEUE(Q, 1)
ENQUEUE(Q, 2)
ENQUEUE(Q, 3)
DEQUEUE(Q)
PRINT FRONT(Q)
A) 1
B) 2
C) 3
D) Queue empty
head → 10 → 20 → 30 → NULL
temp = head
count = 0
WHILE temp != NULL
count = count + 1
temp = temp.next
END WHILE
PRINT count
A) 2
B) 3
C) 4
D) Error
FUNCTION fun(n)
IF n == 0
RETURN 1
ELSE
RETURN n * fun(n-1)
END FUNCTION
PRINT fun(4)
A) 10
B) 16
C) 24
D) 120
FOR i = 1 TO n
FOR j = 1 TO n
PRINT i, j
END FOR
END FOR
Time Complexity?
A) O(n)
B) O(n log n)
C) O(n²)
D) O(2n)
