SQL Quiz

Last modified on: December 6, 2024

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<h3><strong>SQL Quiz</strong></h3>
<p>Challenge your SQL knowledge with this quiz! Each question comes with multiple options to test your understanding of SQL concepts.</p>
<hr />
<h3><strong>Question 1: Basic SELECT Statement</strong></h3>
<p>Which SQL statement is used to retrieve data from a database?</p>
<ul>
<li>A) <code>FETCH</code></li>
<li>B) <code>SELECT</code></li>
<li>C) <code>GET</code></li>
<li>D) <code>DISPLAY</code></li>
</ul>
<p><strong>Answer:</strong> B) <code>SELECT</code></p>
<hr />
<h3><strong>Question 2: Distinct Values</strong></h3>
<p>How do you return only unique values in an SQL query?</p>
<ul>
<li>A) <code>SELECT UNIQUE</code></li>
<li>B) <code>SELECT DISTINCT</code></li>
<li>C) <code>SELECT DIFFERENT</code></li>
<li>D) <code>SELECT FILTER</code></li>
</ul>
<p><strong>Answer:</strong> B) <code>SELECT DISTINCT</code></p>
<hr />
<h3><strong>Question 3: Filtering with WHERE</strong></h3>
<p>What does this query do?</p>
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<pre class="language-php"><code>SELECT * FROM Employees WHERE Age &gt; 30;
</code></pre>
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<ul>
<li>A) Retrieves all employees.</li>
<li>B) Retrieves employees whose age is greater than 30.</li>
<li>C) Updates the age of employees.</li>
<li>D) Deletes employees older than 30.</li>
</ul>
<p><strong>Answer:</strong> B) Retrieves employees whose age is greater than 30.</p>
<hr />
<h3><strong>Question 4: Aggregate Functions</strong></h3>
<p>Which SQL function is used to calculate the total of a numeric column?</p>
<ul>
<li>A) <code>TOTAL</code></li>
<li>B) <code>SUM</code></li>
<li>C) <code>ADD</code></li>
<li>D) <code>COUNT</code></li>
</ul>
<p><strong>Answer:</strong> B) <code>SUM</code></p>
<hr />
<h3><strong>Question 5: Joining Tables</strong></h3>
<p>Which SQL clause is used to combine rows from two or more tables based on a related column?</p>
<ul>
<li>A) <code>MERGE</code></li>
<li>B) <code>CONNECT</code></li>
<li>C) <code>JOIN</code></li>
<li>D) <code>UNION</code></li>
</ul>
<p><strong>Answer:</strong> C) <code>JOIN</code></p>
<hr />
<h3><strong>Question 6: Order Results</strong></h3>
<p>What is the purpose of the <code>ORDER BY</code> clause?</p>
<ul>
<li>A) To filter rows.</li>
<li>B) To sort the result set.</li>
<li>C) To delete rows.</li>
<li>D) To count rows.</li>
</ul>
<p><strong>Answer:</strong> B) To sort the result set.</p>
<hr />
<h3><strong>Question 7: Inserting Data</strong></h3>
<p>What is the correct SQL syntax to insert a new row into the <code>Customers</code> table?</p>
<ul>
<li>A) <code>ADD INTO Customers VALUES ('John', 'Doe', 'New York');</code></li>
<li>B) <code>INSERT INTO Customers VALUES ('John', 'Doe', 'New York');</code></li>
<li>C) <code>NEW INTO Customers VALUES ('John', 'Doe', 'New York');</code></li>
<li>D) <code>INSERT NEW Customers VALUES ('John', 'Doe', 'New York');</code></li>
</ul>
<p><strong>Answer:</strong> B) <code>INSERT INTO Customers VALUES ('John', 'Doe', 'New York');</code></p>
<hr />
<h3><strong>Question 8: Updating Data</strong></h3>
<p>What does this query do?</p>
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<pre class="language-php"><code>UPDATE Products SET Price = 20 WHERE ProductID = 5;
</code></pre>
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<ul>
<li>A) Changes the price of all products to 20.</li>
<li>B) Deletes the product with <code>ProductID = 5</code>.</li>
<li>C) Updates the price of the product with <code>ProductID = 5</code> to 20.</li>
<li>D) Retrieves the product with <code>ProductID = 5</code>.</li>
</ul>
<p><strong>Answer:</strong> C) Updates the price of the product with <code>ProductID = 5</code> to 20.</p>
<hr />
<h3><strong>Question 9: Wildcards</strong></h3>
<p>Which wildcard is used to match any single character in a <code>LIKE</code> clause?</p>
<ul>
<li>A) <code>%</code></li>
<li>B) <code>_</code></li>
<li>C) <code>*</code></li>
<li>D) <code>?</code></li>
</ul>
<p><strong>Answer:</strong> B) <code>_</code></p>
<hr />
<h3><strong>Question 10: NULL Values</strong></h3>
<p>Which statement is true about NULL in SQL?</p>
<ul>
<li>A) <code>NULL</code> is equivalent to zero.</li>
<li>B) <code>NULL</code> is equivalent to an empty string.</li>
<li>C) <code>NULL</code> represents missing or unknown data.</li>
<li>D) <code>NULL</code> values can be compared using the <code>=</code> operator.</li>
</ul>
<p><strong>Answer:</strong> C) <code>NULL</code> represents missing or unknown data.</p>
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<h3>&nbsp;</h3>
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