Add files via upload

Author: lalitchaudhary720

s1- SQL Interview Questions with answers of sales database.sql

@@ -0,0 +1,250 @@
+/*
+This file contains the solutions of all the tasks. After completing the assigned tasks or Questions refer this file for correction
+
+Thank You
+*/
+select * from customers;
+# Sample:- How many customers are male and female?
+
+select gender , count(*) from customers
+group by gender;
+
+/* BASIC SQL QUESTIONS */
+
+# Q1. How many customers do not have DOB information available?
+
+select count(*) from customers where dob is null;
+
+
+# Q2-- How many customers are there in each pincode and gender combination?
+select pincode, gender, count(cust_id) from customers
+group by pincode, gender
+order by pincode desc;
+
+
+# Q3--  Print product name and mrp for products which have more than 50000 MRP? 
+
+select product_name, mrp 
+from products 
+where mrp>50000;
+
+# Q4. How many delivery personal are there in each pincode?
+
+select pincode, count(person_id) from delivery_person
+group by pincode;
+
+/* Q5. For each Pin code, print the count of orders, sum of total amount paid, average amount paid, maximum amount paid,
+ minimum amount paid for the transactions which were paid by 'cash'. 
+Take only 'buy' order types
+*/
+
+select delivery_pincode as pd , count(order_id), sum(total_amount_paid), avg(total_amount_paid), max(total_amount_paid)
+,min(total_amount_paid)
+from orders
+where payment_type="cash" and order_type="buy"
+group by pd;
+
+/*
+Q6. For each delivery_person_id, print the count of orders and 
+total amount paid for product_id = 12350 or 12348 and total units > 8. 
+Sort the output by total amount paid in descending order. Take only 'buy' order types
+*/
+
+select delivery_person_id as pd, count(order_id), sum(total_amount_paid) as tap from orders
+where product_id IN (12348,12350)
+and tot_units>8 and order_type="buy"
+group by pd
+order by tap desc;
+
+# Q7. Print the Full names (first name plus last name) for customers that have email on "gmail.com"?
+select concat(first_name," ",last_name) as Name from customers
+where email like "%gmail%";
+
+# Q8. How many orders had #units between 1-3, 4-6 and 7+? Take only 'buy' order types
+select 
+case 
+when tot_units<3 then "1-3"
+when tot_units>=4 and tot_units<=6 then "4-6"
+else "7+"
+end as cat,
+count(order_id) from orders
+where order_type="buy"
+group by cat
+order by cat;
+
+# Q9. Which pincode has average amount paid more than 150,000? Take only 'buy' order types
+
+select delivery_pincode as pd, avg(total_amount_paid) as avge
+from orders
+where order_type="buy"
+ group by pd
+ having avge>150000;
+
+/* Q10. Create following columns from order_dim data -
+
+order_date
+Order day
+Order month
+Order year */
+ 
+ select order_date, 
+ substr(order_date,1,2) as order_day,
+ substr(order_date,4,2) as order_month,
+ substr(order_date,7) as order_year
+ from orders
+ where order_type="buy";
+
+/* Q11. How many total orders were there in each month and how many of them were returned? Add a column for return rate too.
+return rate = (100.0 * total return orders) / total buy orders
+Hint: You will need to combine SUM() with CASE WHEN
+*/
+ with cte as
+ (
+ select substr(order_date, 4,2) as mon,
+ sum(case when order_type="return" then 1 else 0 end) as Total_Returns,
+ sum(case when order_type="buy" then 1 else 0 end) as Total_buys
+ from orders
+ group by mon)
+ select *, round((total_returns/total_buys)*100,1) as Return_Rate from cte
+ order by return_rate desc;
+ 
+ 
+ # QUESTION ON SQL JOINS
+ 
+ # Q12. How many units have been sold by each brand? Also get total returned units for each brand.
+ 
+ select p.brand, sum(case when order_type="buy" then o.tot_units end)  from products p inner join orders o ON
+ p.product_id=o.product_id
+ group by p.brand;
+ 
+
+ # Q13. How many distinct customers and delivery boys are there in each state?
+
+ select p.state, count(distinct c.cust_id) as Customers, count(distinct dp.person_id) as Delivery_Man 
+ from pincode p inner join customers c
+ ON p.pin_id=c.pincode
+ inner join delivery_person dp 
+ ON p.pin_id=dp.pincode
+ group by p.state;
+
+
+/* Q14. For every customer, print how many total units were ordered, how many units were 
+ordered from their primary_pincode and how many were ordered not from the primary_pincode. 
+Also calulate the percentage of total units which were ordered from 
+primary_pincode(remember to multiply the numerator by 100.0). Sort by the percentage column in descending order.
+*/ 
+
+ select c.cust_id, sum(o.tot_units)as Total_orders,
+ sum(case when c.pincode=o.delivery_pincode then o.tot_units else 0 end) as Same_city,
+ sum(case when c.pincode!=o.delivery_pincode then o.tot_units else 0 end) as Diff_city
+ from customers c 
+ inner join orders o 
+ ON c.cust_id=o.cust_id
+ where o.order_type="buy"
+ group by c.cust_id;
+ 
+ 
+ /* Task 15 
+ For each product name, print the sum of number of units, total amount paid, 
+ total displayed selling price, total mrp of these units, and finally the net discount from selling price 
+ (i.e. 100.0 - 100.0 * total amount paid / total displayed selling price) 
+ AND the net discount from mrp (i.e. 100.0 - 100.0 * total amount paid / total mrp)
+*/
+ 
+ with cte as
+ (
+ select p.product_name, sum(o.tot_units) as units, sum(o.total_amount_paid) as Total_Amount_Paid,
+ sum(o.tot_units*o.displayed_selling_price_per_unit) as Total_Display_Price, sum(o.tot_units*p.mrp) as Total_MRP 
+ from products p left join orders o
+ ON p.product_id = o.product_id
+ group by p.product_name
+ )
+ select *, 100-((total_amount_paid/total_display_price)*100) as Net_SP_discount,
+ 100-((total_amount_paid/total_mrp)*100) as Net_MRP_discount from cte;
+
+ /* Task 16
+ For every order_id (exclude returns), get the product name and calculate the discount 
+ percentage from selling price. Sort by highest discount and print only
+ those rows where discount percentage was above 10.10%.
+ */
+
+ select o.order_id,p.product_name,
+ round((((o.tot_units*o.displayed_selling_price_per_unit)-o.total_amount_paid)/(o.tot_units*o.displayed_selling_price_per_unit))*100,2) as discount
+ from orders o left join products p ON o.product_id=p.product_id
+ where order_type="buy"
+ group by o.order_id, p.product_name
+ having discount>=10.10;
+
+/* Task 17
+Using the per unit procurement cost in product_dim, find which product category has made the most profit in both absolute amount and percentage
+Absolute Profit = Total Amt Sold - Total Procurement Cost
+Percentage Profit = 100.0 * Total Amt Sold / Total Procurement Cost - 100.0 
+*/
+
+with cte as
+(
+select p.category as cat, sum(o.tot_units) as Units_Sold, sum(o.tot_units*procurement_cost_per_unit) as Total_Cost, sum(total_amount_paid) as Revenue
+ from products p left join orders o 
+ON p.product_id=o.product_id
+group by p.category
+) 
+select cat, Revenue-total_cost as Absolute_Profit, 100-((total_cost/revenue)*100) as Percentage_Profit from cte;
+
+/* Task 18
+For every delivery person(use their name), print the total number of order ids (exclude returns) 
+by month in seperate columns i.e. there should be one row for each delivery_person_id and 12 columns for every month in the year
+*/
+
+select dp.name as Delivery_Man, 
+sum(case when substr(o.delivery_date,4,2)=01 then 1 else 0 end) as Jan,
+sum(case when substr(o.delivery_date,4,2)=02 then 1 else 0 end) as Feb,
+sum(case when substr(o.delivery_date,4,2)=03 then 1 else 0 end) as Mar,
+sum(case when substr(o.delivery_date,4,2)=04 then 1 else 0 end) as Apr,
+sum(case when substr(o.delivery_date,4,2)=05 then 1 else 0 end) as May,
+sum(case when substr(o.delivery_date,4,2)=06 then 1 else 0 end) as Jun,
+sum(case when substr(o.delivery_date,4,2)=07 then 1 else 0 end) as Jul,
+sum(case when substr(o.delivery_date,4,2)=08 then 1 else 0 end) as Aug,
+sum(case when substr(o.delivery_date,4,2)=09 then 1 else 0 end) as Sept,
+sum(case when substr(o.delivery_date,4,2)=10 then 1 else 0 end) as Oct,
+sum(case when substr(o.delivery_date,4,2)=11 then 1 else 0 end) as Nov,
+sum(case when substr(o.delivery_date,4,2)=12 then 1 else 0 end) as Decem
+from delivery_person dp inner join orders o
+ON dp.person_id=o.delivery_person_id
+where o.order_type="buy"
+group by dp.name
+order by dp.name;
+
+/* Task 19
+For each gender - male and female - find the absolute and percentage profit (like in Q16) by product name
+*/
+
+
+with cte as
+(
+select c.gender,p.category as cat, sum(tot_units) as Total_units, sum(total_amount_paid) as Amount_Paid,
+sum(p.procurement_cost_per_unit*o.tot_units) as Total_Cost
+from customers c left join orders o
+ON c.cust_id = o.cust_id
+inner join products p
+ON o.product_id=p.product_id
+where o.order_type="buy"
+group by c.gender,p.category
+order by c.gender
+)
+select gender,cat, Amount_paid-total_cost as Abs_Profit,
+100-((total_cost/amount_paid)*100) as Profit from cte;
+ 
+ 
+ /* Task 20 
+ Generally the more numbers of units you buy, the more discount seller will give you.
+ For 'Dell AX420' is there a relationship between number of units ordered and average discount 
+ from selling price? Take only 'buy' order types
+ */
+ 
+select o.tot_units, (avg(o.displayed_selling_price_per_unit*o.tot_units)-avg(o.total_amount_paid)) as Average_discount 
+from orders o inner join products p
+ON o.product_id=p.product_id
+where p.product_name="Dell AX420" and o.order_type="buy"
+group by o.tot_units
+order by o.tot_units;
+