Find the most common value (mode) in a specific column.

This question was asked in Interview at black rock. Read more

Company: BlackRock

CTC: 26LPA

Source: LinkedIn

SQL Interview Question

Q. Find the most common value (mode) in a specific column.

-- Create the Products table
CREATE TABLE Products (
    ProductID INT PRIMARY KEY,
    ProductName VARCHAR(100),
    Category VARCHAR(50),
    Price DECIMAL(10, 2)
);

-- Insert sample data into Products table
INSERT INTO Products VALUES
(1, 'Laptop', 'Electronics', 800.00),
(2, 'Laptop', 'Electronics', 300.00),
(3, 'Headphones', 'Electronics', 50.00),
(4, 'Laptop', 'Electronics', 800.00),
(5, 'Tablet', 'Electronics', 300.00),
(6, 'Tablet', 'Electronics', 300.00),
(7, 'Chair', 'Furniture', 120.00),
(8, 'Table', 'Furniture', 250.00),
(9, 'Laptop', 'Electronics', 800.00),
(10, 'Desk', 'Furniture', 200.00);

See this code on db-fiddle

Solution

SELECT 
    ProductName,
    COUNT(*) AS Frequency
FROM 
    Products
GROUP BY 
    ProductName
ORDER BY 
    Frequency DESC
LIMIT 1;

Explanation

We have selected ProductName along with the count of rows as Frequency, grouping the data by ProductName. To display the product with the highest frequency at the top of the table, we used ORDER BY Frequency DESC. Finally, the LIMIT clause ensures that only the top record is selected.

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