# 9 Acer SQL Interview Questions (Updated 2024)

Updated on

March 3, 2024

At Acer, SQL is typically used for analyzing customer usage patterns across their tech products and optimizing supply chain logistics based on market data insights. That's why Acer almost always evaluates jobseekers on SQL coding questions during interviews for Data Science and Data Engineering positions.

To help you prepare for the Acer SQL interview, this blog covers 9 Acer SQL interview questions – how many can you solve?

## 9 Acer SQL Interview Questions

### SQL Question 1: Compute AVG Number of Stars Per Product Per Month.

Given the dataset, can you calculate the average rating () per product () per month of year ()? Assume that is in 'YYYY-MM-DD' format.

##### Example Input:
review_iduser_idsubmit_dateproduct_idstars
110012022-06-01100015
210022022-06-03100013
310032022-06-05100022
410042022-06-07100013
510052022-07-01100025
610062022-07-03100024
710072022-07-05100023
810082022-07-07100025

A possible query to answer this question is as follows:

This query extracts the month from the using the function. It then groups by the extracted month and to calculate the , or average number of stars, per product per month. Finally, it orders the output by and the month for easier interpretability.

Expected output:

##### Example Output:
mthproductavg_stars
6100013.67
6100022.00
7100024.25

For more window function practice, try this Uber SQL problem within DataLemur's interactive SQL code editor:

### SQL Question 2: Analyzing Sales Data for Acer

As a data analyst at Acer, consider you have two tables: and . The table contains information about the products Acer sells, and the table contains sales data for these products. You are tasked to find out the total sales volume for each product category for the current year.

#### sample table:

product_idnamecategory
P1001LaptopComputing
P1002DesktopComputing
P1003MonitorPeripherals
P1004PrinterPeripherals
P1005TabletMobile

#### sample table:

sale_idproduct_idsale_datequantity
S2001P100101/12/20215
S2002P100102/24/20213
S2003P100303/15/20214
S2004P100404/18/20212
S2005P100512/30/20216

#### Explanation

This PostgreSQL query joins the and tables on . It uses the function to filter out the sales data for the current year. The clause groups the results by product , and the function gives the total sales volume for each category.

### SQL Question 3: What does the operator do?

The / operator is used to remove to return all rows from the first SELECT statement that are not returned by the second SELECT statement.

Note that is available in PostgreSQL and SQL Server, while MINUS is available in MySQL and Oracle (but don't worry about knowing which DBMS supports which exact commands since Acer interviewers aren't trying to trip you up on memorizing SQL syntax).

For a tangible example of in PostgreSQL, suppose you were doing an HR Analytics project for Acer, and had access to Acer's contractors and employees data. Assume that some employees were previously contractors, and vice versa, and thus would show up in both tables.

You could use operator to find all contractors who never were a employee using this query:

### SQL Question 4: Filter Acer Customer Records by Purchase Date and Laptop Model

In a typical business setting, we'd often want to know customer activities and trends. In this case, Acer wants to analyze customers based on purchase date and specific laptop models.

Assume you are given a 'customers' table and a 'purchases' table. The 'customers' table contains customer records, and the 'purchases' table contains purchase records.

Now, Acer wants to identify all customers who have purchased the laptop model "Predator 17X" during the year 2021.

Please write a SQL query to retrieve all the relevant customer records.

##### Example Input
customer_idfirst_namelast_nameemail
101JohnDoejohndoe@gmail.com
102JaneSmithjanesmith@gmail.com
103RobertJohnsonrobertjohnson@gmail.com
104MichaelWilliamsmichaelwilliams@gmail.com
##### Example Input
purchase_idcustomer_idlaptop_modelpurchase_date
1101Aspire 52020-12-01
2102Predator 17X2021-03-15
3103Aspire 32021-11-10
4104Predator 17X2021-07-25
5102Aspire 72021-06-20
##### Example Output
customer_idfirst_namelast_nameemail
102JaneSmithjanesmith@gmail.com
104MichaelWilliamsmichaelwilliams@gmail.com

Here is a PostgreSQL solution for the problem:

In this query, we first make a JOIN operation on 'customers' and 'purchases' tables, then filtering the data such that the laptop model is "Predator 17X" and the purchase year is 2021.

The EXTRACT function is used to pull out the Year part from the 'purchase_date' column. If it matches 2021, the record is included in the results.

### SQL Question 5: What are the different kinds of joins in SQL?

Joins in SQL allow you to combine data from different tables based on a shared key or set of keys.

Four JOIN types are available in SQL. For an example of each one, say you had sales data exported from Acer's Salesforce CRM stored in a PostgreSQL database, and had access to two tables: and .

• : retrieves rows from both tables where there is a match in the shared key or keys. For example, an INNER JOIN between the Sales table and the Customers table would retrieve only the rows where the customer_id in the Sales table matches the customer_id in the table.
• : retrieves all rows from the left table (in this case, the sales table) and any matching rows from the right table (the table). If there is no match in the right table, NULL values will be returned for the right table's columns.
• : retrieves all rows from the right table (in this case, the customers table) and any matching rows from the left table (the sales table). If there is no match in the left table, NULL values will be returned for the left table's columns.
• : retrieves all rows from both tables, regardless of whether there is a match in the shared key or keys. If there is no match, NULL values will be returned for the columns of the non-matching table.

### SQL Question 6: Find the Total Sales of Each Acer Product

Acer Inc is a multinational hardware and electronics corporation that sells different types of computer hardware products like desktops, laptops, tablets, servers, storage devices, Virtual Reality devices, displays, smartphones and peripherals, and also provides e-business services to businesses, government and education. Each product has a unique product_id and their sales are logged in the 'sales' table. Assume each entry in the 'sales' table represents a single unit sale of that product. Write an SQL query which calculates the total sales of each Acer product.

##### Example Input:
sale_idsale_dateproduct_idprice
12562022-07-01 00:00:00784521100
45282022-07-15 00:00:00501011350
79812022-07-22 00:00:00784521100
61822022-08-01 00:00:0069856900
91922022-08-12 00:00:00501011350
74572022-08-18 00:00:0069856900

This query will give the total sales of each product. is used to aggregate the sales table by , enabling calculation of sum of for each . The function calculates the sum of all values in for each group. The result is a list of unique s alongside the total revenue generated by each product.

### SQL Question 7: What do foreign key's do?

A foreign key is a column or group of columns in a table that refers to the primary key in another table. The foreign key constraint helps maintain referential integrity between the two tables. The table with the foreign key is called the child table, while the table with the candidate key is called the parent or referenced table.

For example, consider a database with two tables: and customer_idcustomer_idcustomer_id` column in Acer customers table.

### SQL Question 8: Calculate Average Product Ratings and Deviation

Acer is looking to better understand its product ratings. Your task is to write a SQL query to calculate the monthly average product rating and rating deviation for each Acer product. Additionally, since Acer often releases new software updates, the company is interested in the changes in ratings post-update. For this use case, you need to compute the average rating and rating deviation three days after each software update.

Assume you have two tables -- 'reviews' and 'updates' -- with the following structure and example data:

##### Example Input:
review_iduser_idsubmit_dateproduct_idrating
11012022-01-0110014
21022022-01-0210023
31032022-01-0310035
41042022-01-0410013
51052022-02-0110015
##### Example Input:
update_idupdate_dateproduct_id
12022-01-021001
22022-01-041003

Here is a SQL (PostgreSQL) solution to the problem:

This SQL query calculates the average rating and rating deviation for every product, for every month, after any software update within a three-day window. The AVG() function is used to calculate the average rating, and the SQRT() and POWER() functions are used to calculate the rating deviation. The query uses the INNER JOIN clause to only consider reviews for products that had a software update and were reviewed within three days of the update.

### SQL Question 9: Sales Trend Analysis

As an analyst at Acer, one of your responsibilities is tracking sales trends for different product models. The company is interested in understanding the month-to-month sales in quantity for different laptop models. Build a SQL query that provides a month-over-month sales quantity report of Acer's laptop models for the year 2022.

##### Example Input:
sale_idsale_dateproduct_idquantity
101/05/2022L1013
201/12/2022L1025
301/18/2022L1022
402/04/2022L1016
502/21/2022L1024
603/09/2022L1015
703/15/2022L1023
803/20/2022L1011

The output should list each model, each month in the year 2022 and how many that model sold that month:

##### Example Output:
monthproduct_idtotal_quantity
1L1013
1L1027
2L1016
2L1024
3L1016
3L1023

This SQL query extracts the month from the date of the sales, groups the data by the month and the product_id and then sums up the quantity of laptops sold for each model each month. The result is ordered by month and product_id to easily view the sales trend for each laptop over the months in 2022.

### Preparing For The Acer SQL Interview

The key to acing a Acer SQL interview is to practice, practice, and then practice some more! In addition to solving the earlier Acer SQL interview questions, you should also solve the 200+ tricky sql questions on DataLemur which come from companies like Netflix, Google, and Amazon.

Each SQL question has multiple hints, step-by-step solutions and most importantly, there is an interactive SQL code editor so you can instantly run your SQL query answer and have it graded.

To prep for the Acer SQL interview it is also useful to solve SQL questions from other tech companies like:

In case your SQL foundations are weak, forget about diving straight into solving questions – refresh your SQL knowledge with this SQL interview tutorial.

This tutorial covers things like LEAD/LAG and creating summary stats with GROUP BY – both of which pop up routinely during Acer interviews.

### Acer Data Science Interview Tips

#### What Do Acer Data Science Interviews Cover?

In addition to SQL interview questions, the other topics to practice for the Acer Data Science Interview are:

#### How To Prepare for Acer Data Science Interviews?

The best way to prepare for Acer Data Science interviews is by reading Ace the Data Science Interview. The book's got:

• 201 Interview Questions from FAANG tech companies
• A Refresher covering Stats, ML, & Data Case Studies
• Amazing Reviews (900+ reviews, 4.5-star rating)