Retail Sales Analysis PostgresSQL.sql

-- SQL Retail Sales Analysis
-- Create Table
CREATE TABLE retail_sales
            (
                transaction_id INT PRIMARY KEY,	
                sale_date DATE,	 
                sale_time TIME,	
                customer_id	INT,
                gender	VARCHAR(15),
                age	INT,
                category VARCHAR(15),	
                quantity	INT,
                price_per_unit FLOAT,	
                cogs	FLOAT,
                total_sale FLOAT
            );
--
SELECT * FROM retail_sales
LIMIT 10

---

-- Data Cleaning
SELECT * FROM retail_sales
WHERE transaction_id IS NULL

---

SELECT * FROM retail_sales
WHERE 
    transaction_id IS NULL
    OR
    sale_date IS NULL
    OR 
    sale_time IS NULL
    OR
    gender IS NULL
    OR
    category IS NULL
    OR
    quantity IS NULL
    OR
    cogs IS NULL
    OR
    total_sale IS NULL;

	
-- 
DELETE FROM retail_sales
WHERE 
    transaction_id IS NULL
    OR
    sale_date IS NULL
    OR 
    sale_time IS NULL
    OR
    gender IS NULL
    OR
    category IS NULL
    OR
    quantity IS NULL
    OR
    cogs IS NULL
    OR
    total_sale IS NULL;


-- Data Exploration

-- How many sales we have?
SELECT COUNT(*) as total_sale FROM retail_sales

-- How many uniuque customers we have ?
SELECT COUNT(DISTINCT customer_id) as total_sale FROM retail_sales

-- How many category do we have?
SELECT DISTINCT category FROM retail_sales

---- Data Analysis & Business Key Problems & Answers

-- Q.1 Write a SQL query to retrieve all columns for sales made on '2022-11-05
-- Q.2 Write a SQL query to retrieve all transactions where the category is 'Clothing' and the quantity sold is more than 10 in the month of Nov-2022
-- Q.3 Write a SQL query to calculate the total sales (total_sale) for each category.
-- Q.4 Write a SQL query to find the average age of customers who purchased items from the 'Beauty' category.
-- Q.5 Write a SQL query to find all transactions where the total_sale is greater than 1000.
-- Q.6 Write a SQL query to find the total number of transactions (transaction_id) made by each gender in each category.
-- Q.7 Write a SQL query to calculate the average sale for each month. Find out best selling month in each year
-- Q.8 Write a SQL query to find the top 5 customers based on the highest total sales 
-- Q.9 Write a SQL query to find the number of unique customers who purchased items from each category.
-- Q.10 Write a SQL query to create each shift and number of orders (Example Morning <=12, Afternoon Between 12 & 17, Evening >17)


--SQL queries for the questions

-- Q.1 Write a SQL query to retrieve all columns for sales made on '2022-11-05'
Select *
From retail_sales
where sale_date = '2022-11-05'

-- Q.2 Write a SQL query to retrieve all transactions where the category is 'Clothing' and the quantity sold is more than 10 in the month of Nov-2022
SELECT  *
FROM retail_sales
WHERE 
    category = 'Clothing'
    AND 
    TO_CHAR(sale_date, 'YYYY-MM') = '2022-11'
    AND
    quantity >= 4

-- Q.3 Write a SQL query to calculate the total sales (total_sale) and total orders for each category.

SELECT 
    category,
    SUM(total_sale) as net_sale,
    COUNT(*) as total_orders
FROM retail_sales
GROUP BY 1

-- Q.4 Write a SQL query to find the average age of customers who purchased items from the 'Beauty' category.

SELECT
    ROUND(AVG(age), 2) as avg_age
FROM retail_sales
WHERE category = 'Beauty'

-- Q.5 Write a SQL query to find all transactions where the total_sale is greater than 1000.

SELECT * FROM retail_sales
WHERE total_sale > 1000

-- Q.6 Write a SQL query to find the total number of transactions (transaction_id) made by each gender in each category.

SELECT 
    category,
    gender,
    COUNT(*) as total_trans
FROM retail_sales
GROUP 
    BY 
    category,
    gender
ORDER BY 1

-- Q.7 Write a SQL query to calculate the average sale for each month. Find out best selling month in each year

SELECT 
       year,
       month,
    avg_sale
FROM 
(    
SELECT 
    EXTRACT(YEAR FROM sale_date) as year,
    EXTRACT(MONTH FROM sale_date) as month,
    AVG(total_sale) as avg_sale,
    RANK() OVER(PARTITION BY EXTRACT(YEAR FROM sale_date) ORDER BY AVG(total_sale) DESC) as rank
FROM retail_sales
GROUP BY 1, 2
) as t1
WHERE rank = 1

-- Q.8 Write a SQL query to find the top 5 customers based on the highest total sales 

SELECT 
    customer_id,
    SUM(total_sale) as total_sales
FROM retail_sales
GROUP BY 1
ORDER BY 2 DESC
LIMIT 5

-- Q.9 Write a SQL query to find the number of unique customers who purchased items from each category.
SELECT 
    category,    
    COUNT(DISTINCT customer_id) as cnt_unique_cs
FROM retail_sales
GROUP BY category

-- Q.10 Write a SQL query to create each shift and number of orders (Example Morning <12, Afternoon Between 12 & 17, Evening >17)

WITH hourly_sale
AS
(
SELECT *,
    CASE
        WHEN EXTRACT(HOUR FROM sale_time) < 12 THEN 'Morning'
        WHEN EXTRACT(HOUR FROM sale_time) BETWEEN 12 AND 17 THEN 'Afternoon'
        ELSE 'Evening'
    END as shift
FROM retail_sales
)
SELECT 
    shift,
    COUNT(*) as total_orders    
FROM hourly_sale
GROUP BY shift

-- End of project