Test Your MySQL DISTINCT Knowledge with this Fun Quiz

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True / False

In MySQL, the DISTINCT keyword is used to remove duplicate rows from the result set.

True False

The DISTINCT keyword ensures that only unique rows are returned in the result set.

True / False

Using DISTINCT in MySQL can be applied to multiple columns in a single query.

True False

When DISTINCT is applied to multiple columns, it ensures that each combination of values is unique in the result set.

True / False

In MySQL, the DISTINCT keyword can only be used with numeric columns.

True False

The DISTINCT keyword can be used with any type of column, including numeric, string, and date types.

True / False

In MySQL, using DISTINCT with ORDER BY can change the order of the result set.

True False

The DISTINCT keyword does not affect the ordering of the result set. The ORDER BY clause is used to sort the results.

True / False

In MySQL, when using DISTINCT, the column alias can be used in the ORDER BY clause.

True False

Column aliases can be referenced in the ORDER BY clause when using DISTINCT.

True / False

In MySQL, the DISTINCT keyword can be used with aggregate functions like SUM and COUNT.

True False

The DISTINCT keyword can be used within aggregate functions to consider only unique values.

True / False

In MySQL, using DISTINCT on a column with NULL values will return only one NULL in the result set.

True False

When using DISTINCT, only one NULL value is returned in the result set, as NULL is considered a distinct value.

True / False

In MySQL, you can use the DISTINCT keyword in a subquery within the FROM clause.

True False

The DISTINCT keyword can be used in subqueries to return unique rows before further processing in the main query.

True / False

In MySQL, the DISTINCT keyword can be used with the GROUP BY clause to further filter unique groups.

True False

The GROUP BY clause already groups the rows based on unique values, so using DISTINCT with GROUP BY is redundant.

Q10

True / False

In MySQL certification exams, it's stated that using DISTINCT with LIMIT will always return the exact number of unique rows specified by LIMIT.

True False

When using DISTINCT with LIMIT, the number of rows returned may be less than the specified limit if there are not enough unique rows in the result set.

Q11

Single Choice

Which keyword is used in MySQL to eliminate duplicate rows from the result set?

UNIQUE DISTINCT DISTINCTROWDIFFERENT

The DISTINCT keyword in MySQL is used to return only distinct (different) values from a column in a query.

Q12

Single Choice

What will this query return?

SQL Code

Consider the following MySQL query :
SELECT DISTINCT city FROM customers;

All the rows in the customers table Only distinct cities from the customers table All cities, including duplicates, from the customers tableNone of the above

The DISTINCT keyword ensures that duplicate city names are removed from the result set.

Q13

Single Choice

Which of the following statements is true about the MySQL DISTINCT keyword?

It can be used with both single and multiple columns It can only be used with a single column It removes NULL valuesIt is used to sort the result set

The DISTINCT keyword can be applied to one or more columns in a MySQL query to remove duplicates.

Q14

Single Choice

Which of the following best describes the result set?

SQL Code

Given the following MySQL query: SELECT DISTINCT first_name, last_name FROM employees;

Only distinct first_name values Only distinct last_name values Unique pairs of first_name and last_nameAll rows in the employees table

The DISTINCT keyword applies to the combination of columns specified, so this query will return distinct pairs of first_name and last_name.

Q15

Single Choice

What is the output of the following MySQL query if the table orders contains 10 rows with 2 distinct order_date values?

2 10 51

The query counts the number of unique order_date values, which in this case is 2.

Q16

Single Choice

Which of the following will be true about the output?

SQL Code

Consider the following MySQL query:SELECT DISTINCT department_id FROM employees ORDER BY department_id DESC;

The result set will contain duplicate department IDs The result set will be sorted in ascending order by department_id The result set will contain distinct department IDs sorted in descending orderThe result set will contain distinct department IDs, but the order is not guaranteed

The DISTINCT keyword ensures unique values, and the ORDER BY clause sorts them in descending order.

Q17

Single Choice

If the employees table has 1000 rows, what does this query return?

SQL Code

Given the following MySQL query:SELECT DISTINCT salary FROM employees WHERE salary > 50000 ORDER BY salary;

Distinct salaries greater than 50000, sorted in ascending order All salaries greater than 50000, sorted in ascending order Distinct salaries greater than 50000, in any orderAll distinct salaries in the employees table, sorted in ascending order

The query filters salaries greater than 50000, applies DISTINCT to remove duplicates, and sorts the result in ascending order.

Q18

Single Choice

How does MySQL handle NULL values when using the DISTINCT keyword?

NULL values are ignored Only one NULL value is included in the result set All NULL values are includedMySQL throws an error when NULL values are present

When using DISTINCT, MySQL considers NULL as a unique value, so only one NULL is included in the result set.

Q19

Single Choice

What will be the result of the following MySQL query:

SQL Code

SELECT DISTINCT COUNT(product_id) FROM sales WHERE amount > 100;

The total count of distinct product_ids with amount greater than 100 The distinct count of product_id where amount is greater than 100 1 if any product_id has an amount greater than 100The total count of product_ids with amount greater than 100

The query first applies DISTINCT to the product_id where amount is greater than 100, then counts these distinct values.

Q20

Single Choice

In a certification exam scenario, which MySQL query will return the number of distinct employee_id values from the attendance table?

SELECT COUNT(DISTINCT employee_id) FROM attendance; SELECT DISTINCT COUNT(employee_id) FROM attendance; SELECT COUNT(UNIQUE employee_id) FROM attendance;SELECT COUNT(*) FROM attendance WHERE DISTINCT employee_id;

The correct way to count distinct values of a column in MySQL is by using COUNT(DISTINCT column_name). The other options are either incorrect syntax or logically incorrect.

Q21

Multiple Choice

Which query correctly selects unique values for the 'department' column from the 'employees' table?

SQL Code

SELECT DISTINCT department
FROM employees;

SELECT DISTINCT department FROM employees; SELECT department FROM employees; SELECT department, COUNT(*) FROM employees GROUP BY department;SELECT DISTINCT department FROM employees ORDER BY department;

The DISTINCT keyword is used to return only distinct (unique) values in the 'department' column.

Q22

Multiple Choice

Identify the correct SQL query that retrieves unique combinations of 'department' and 'position' from the 'employees' table.

SQL Code

SELECT DISTINCT department, position
FROM employees;

SELECT DISTINCT department, position FROM employees; SELECT department, position FROM employees; SELECT DISTINCT department FROM employees GROUP BY position;SELECT DISTINCT department, position FROM employees ORDER BY department, position;

The DISTINCT keyword is applied to both 'department' and 'position' to return unique combinations of these columns.

Q23

Multiple Choice

Which query correctly retrieves unique 'customer_id' values from the 'orders' table?

SQL Code

SELECT DISTINCT customer_id
FROM orders;

SELECT DISTINCT customer_id FROM orders; SELECT customer_id FROM orders GROUP BY customer_id; SELECT customer_id FROM orders ORDER BY customer_id;SELECT DISTINCT customer_id FROM orders ORDER BY customer_id;

The DISTINCT keyword ensures that only unique 'customer_id' values are returned from the 'orders' table.

Q24

Multiple Choice

Determine the correct query to select distinct values from the 'product_name' column in the 'products' table.

SQL Code

SELECT DISTINCT product_name
FROM products;

SELECT DISTINCT product_name FROM products; SELECT product_name FROM products GROUP BY product_name; SELECT DISTINCT product_name FROM products ORDER BY product_name;SELECT product_name FROM products ORDER BY product_name;

Using the DISTINCT keyword, the query returns only unique values from the 'product_name' column in the 'products' table.

Q25

Multiple Choice

Which query retrieves distinct 'category' values from the 'items' table, sorted by 'category' in ascending order?

SQL Code

SELECT DISTINCT category
FROM items
ORDER BY category ASC;

SELECT DISTINCT category FROM items ORDER BY category ASC; SELECT category FROM items GROUP BY category ORDER BY category; SELECT DISTINCT category FROM items ORDER BY category DESC;SELECT DISTINCT category FROM items;

The DISTINCT keyword is used to retrieve unique 'category' values, and the ORDER BY clause sorts them in ascending order.

Q26

Multiple Choice

Which query retrieves unique combinations of 'city' and 'state' from the 'customers' table, sorted by 'state'?

SQL Code

SELECT DISTINCT city, state
FROM customers
ORDER BY state;

SELECT DISTINCT city, state FROM customers ORDER BY state; SELECT city, state FROM customers GROUP BY city, state ORDER BY state; SELECT DISTINCT city, state FROM customers;SELECT city, state FROM customers ORDER BY state;

The DISTINCT keyword is used to return unique combinations of 'city' and 'state', with the result set sorted by 'state'.

Q27

Multiple Choice

Determine the correct query to retrieve distinct 'supplier_name' and 'contact_name' pairs from the 'suppliers' table.

SQL Code

SELECT DISTINCT supplier_name, contact_name
FROM suppliers;

SELECT DISTINCT supplier_name, contact_name FROM suppliers; SELECT supplier_name, contact_name FROM suppliers GROUP BY supplier_name, contact_name; SELECT DISTINCT supplier_name FROM suppliers ORDER BY contact_name;SELECT supplier_name, contact_name FROM suppliers;

The DISTINCT keyword ensures that only unique combinations of 'supplier_name' and 'contact_name' are returned.

Q28

Multiple Choice

Which query retrieves distinct 'order_status' values from the 'orders' table, limited to the first 5 unique values?

SQL Code

SELECT DISTINCT order_status
FROM orders
LIMIT 5;

SELECT DISTINCT order_status FROM orders LIMIT 5; SELECT order_status FROM orders GROUP BY order_status LIMIT 5; SELECT DISTINCT order_status FROM orders;SELECT DISTINCT order_status FROM orders ORDER BY order_status LIMIT 5;

The DISTINCT keyword returns unique 'order_status' values, and the LIMIT clause restricts the result set to the first 5 unique values.

Q29

Multiple Choice

Which SQL query correctly retrieves unique 'employee_id' and 'project_id' combinations from the 'assignments' table?

SQL Code

SELECT DISTINCT employee_id, project_id
FROM assignments;

SELECT DISTINCT employee_id, project_id FROM assignments; SELECT employee_id, project_id FROM assignments GROUP BY employee_id, project_id; SELECT DISTINCT employee_id FROM assignments;SELECT DISTINCT project_id FROM assignments;

The DISTINCT keyword is applied to 'employee_id' and 'project_id' to return unique combinations of these columns.

Q30

Multiple Choice

Identify the correct SQL query to retrieve distinct 'country' values from the 'suppliers' table, ordered by 'country' in descending order.

SQL Code

SELECT DISTINCT country
FROM suppliers
ORDER BY country DESC;

SELECT DISTINCT country FROM suppliers ORDER BY country DESC; SELECT country FROM suppliers GROUP BY country ORDER BY country DESC; SELECT DISTINCT country FROM suppliers;SELECT country FROM suppliers ORDER BY country ASC;

The DISTINCT keyword is used to select unique 'country' values, and the ORDER BY clause sorts them in descending order.

MySQL Database Quiz Questions