Databases - Upwork

Question: Which one of the following correctly selects rows from the table myTable that have NULL in column column1?
A
SELECT * FROM myTable WHERE column1 IS NULL

B
SELECT * FROM myTable WHERE column1 = NULL

C
SELECT * FROM myTable WHERE column1 EQUALS NULL

D
SELECT * FROM myTable WHERE column1 NOT NULL

E
SELECT * FROM myTable WHERE column1 CONTAINS NULL

Note: Not available
1. Report
Question: Is the FROM clause necessary in every SELECT statement?
A
Yes

B
No

Note: Not available
1. Report
Question: Which command will make a backup on the whole database except the tables sessions and log?
A
mysqldump db_name sessions log > backup.sql

B
mysqldump db_name | grep -vv -E "sessions|log" > backup.sql

C
mysqldump db_name --ignore-table db_name.sessions db_name.log > backup.sql

D
mysqldump db_name --except-table=db_name.sessions --except-table=db_name.log > backup.sql

Note: Not available
1. Report
Question: Which graph traversal algorithm uses a queue to keep track of the vertices which need to be processed?
A
Breadth-first search

B
Depth-first search

Note: Not available
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Question: A simple graph with n vertices and k components can have at the most _______.
A
n edges

B
n-k edges

C
(n-k)(n-k-1)/2 edges

D
(n-k)(n-k+1)/2 edges

Note: Not available
1. Report
Question: What is the minimum number of edges which must be removed from a complete bipartite graph of six nodes K(6) so that the remaining graph is a planar?
A
2

B
3

C
4

D
6

Note: Not available
1. Report
Question: Which feature of heaps allows them to be efficiently implemented using a partially filled array?
A
Heaps are binary search trees

B
Heaps are complete binary trees

C
Heaps are full binary trees

D
Heaps contain only integer data

Note: Not available
1. Report
Question: What happens if you make a recursive call without making the problem smaller?
A
The operating system detects the infinite recursion because of the "repeated state"

B
The program keeps running until you press Ctrl-C

C
The results are non-deterministic

D
The run-time stack overflows, halting the program

Note: Not available
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Question: Tree algorithms typically run in time O(d) . What is d?
A
The depth of the tree

B
The number of divisions at each level

C
The number of nodes in the tree

D
The total number of entries in all the nodes of the tree

Note: Not available
1. Report
Question: Here is a code for an integer variable n while (n > 0) { n = n/10; // Use integer division } What is the worst case scenario analysis for the above loop?
A
O(1)

B
O(log n)

C
O(n)

D
O(n2)

Note: Not available
1. Report

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Question: Which one of the following correctly selects rows from the table myTable that have NULL in column column1?

Question: Is the FROM clause necessary in every SELECT statement?

Question: Which command will make a backup on the whole database except the tables sessions and log?

Question: Which graph traversal algorithm uses a queue to keep track of the vertices which need to be processed?

Question: A simple graph with n vertices and k components can have at the most _______.

Question: What is the minimum number of edges which must be removed from a complete bipartite graph of six nodes K(6) so that the remaining graph is a planar?

Question: Which feature of heaps allows them to be efficiently implemented using a partially filled array?

Question: What happens if you make a recursive call without making the problem smaller?

Question: Tree algorithms typically run in time O(d) . What is d?

Question: Here is a code for an integer variable n while (n > 0) { n = n/10; // Use integer division } What is the worst case scenario analysis for the above loop?