# 8 Allstate SQL Interview Questions (Updated 2024)

Updated on

August 11, 2024

At Allstate Insurance, SQL is used for analyzing policyholder data trends by identifying high-risk customer segments, as well as optimizing risk management models, such as predicting claim frequencies and severities. This is the reason why Allstate includes SQL questions during interviews for Data Science, Analytics, and & Data Engineering jobs.

## 8 Allstate Insurance SQL Interview Questions

### SQL Question 1: Calculate Customer Claims Average Amount Per Month

At Allstate, an insurance analyst may want to analyze the average amount of claims made per customer each month, in order to track patterns, identify potential fraud, and provide better customer service. Your goal is to write a PostgreSQL query using window functions to calculate the monthly average claim amount per customer.

Consider a table with the following schema:

##### Example Input:
claim_idcustomer_idclaim_dateclaim_amount(USD)
101103401/06/20223000
102105601/10/20225000
103103401/20/20224000
104105602/15/20223500
105103402/25/20225000

You can assume that is unique and is of the format "mm/dd/yyyy".

##### Example Output:
monthcustomer_idavg_claim_amount(USD)
110343500
110565000
210345000
210563500

You can write the following PostgreSQL query:

This query uses a window function to compute the average claim amount per per month. The clause segregates the data into partitions based on and . The function then operates on these partitions to give average claim amount per customer per month. Note that use of clause in the end to ensure that the output is ordered by month and then by .

To solve a similar window function question on DataLemur's free interactive coding environment, try this Google SQL Interview Question:

### SQL Question 2: Highly-Paid Employees

Imagine there was a table of Allstate employee salary data. Write a SQL query to find all employees who earn more than their direct manager.

#### Allstate Example Input:

employee_idnamesalarydepartment_idmanager_id
1Emma Thompson38001
2Daniel Rodriguez2230110
3Olivia Smith800018
4Noah Johnson680028
5Sophia Martinez1750110
8William Davis70002NULL
10James Anderson40001NULL

#### Example Output:

employee_idemployee_name
3Olivia Smith

This is the output because Olivia Smith earns \$8,000, surpassing her manager, William Davis who earns 7,800.

Write a SQL query for this interview question and run your code right in DataLemur's online SQL environment:

First, we perform a SELF-JOIN where we treat the first table () as the managers' table and the second table () as the employees' table. Then we use a clause to filter the results, ensuring we only get employees whose salaries are higher than their manager's salary.

If the code above is hard to understand, you can find a step-by-step solution here: Well Paid Employees.

### SQL Question 3: Can you describe the concept of database denormalization in layman's terms?

Denormalization is a technique used to improve the read performance of a database, typically at the expense of some write performance.

By adding redundant copies of data or grouping data together in a way that does not follow normalization rules, denormalization improves the performance and scalability of a database by eliminating costly join operations, which is important for OLAP use cases that are read-heavy and have minimal updates/inserts.

### SQL Question 4: Retrieve Policy Holders Details

At Allstate, an insurance policy database is maintained which contains various fields like policy_id, policy_holder_name, policy_type, start_date, and end_date. You are required to write a query that filters out the policy holders who have a home insurance policy (policy_type = 'home') that started in 2022.

##### Example Input:
policy_idpolicy_holder_namepolicy_typestart_dateend_date
110John Smithcar2022-02-152023-02-15
111Jane Doehome2022-06-102023-06-10
113Lisa Choihome2022-08-012023-08-01
114Robert Kimcar2022-09-252023-09-25
##### Example Output:
policy_idpolicy_holder_namestart_date
111Jane Doe2022-06-10
113Lisa Choi2022-08-01

In this solution, the clause is used to filter the records where the policy type is 'home' and the start year is 2022. function is used to get the year from the start_date field.

### SQL Question 5: In database design, what do foreign keys 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.

For example, let's look at the Allstate sales database:

##### :
order_idproduct_idcustomer_idquantity
122212
233311
344423
455531

In this table, and could both be foreign keys. They reference the primary keys of other tables, such as a Products table and a Customers table, respectively. This establishes a relationship between the table and the other tables, such that each row in the sales database corresponds to a specific product and a specific customer.

### SQL Question 6: Find the Average Insurance Claim per Policy

Allstate is an insurance company and the average claims made per policy could be an interesting data point to assess. Say that Allstate wants to evaluate and compare the average claim amount made under its different insurance policies in the year 2021. You are given a table that contains all the insurance policies, and a table that records each claim made. Please write a SQL query to find the average claim amount for each insurance policy type for the year 2021.

##### Example Input:
policy_idholder_idpolicy_type
P101H001Home
P102H002Car
P103H003Life
P104H004Home
P105H005Motorcycle
##### Example Input:
claim_idpolicy_idclaimed_amountdate_claimed
C001P10150002021-06-01
C002P10120002021-07-01
C003P10460002021-08-01
C004P103100002021-09-01
C005P10230002021-09-01
##### Example Output:
policy_typeaverage_claim
Home4333.33
Life10000
Car3000

The above query first joins the and tables using the . It then selects the from the table and calculates the average of the from the table. The query filters for the claims made in the year 2021 using the clause, and groups the result by to get the average claim amount for each policy.

To practice a very similar question try this interactive Amazon Highest-Grossing Items Question which is similar for needing to aggregate and rank grouped data or this Stripe Repeated Payments Question which is similar for involving analysis of transactions and identifying certain patterns.

### SQL Question 7: What are the similarities and differences between a clustered and non-clustered index?

A clustered index is an index where the order of the rows in the database corresponds to the order of the rows in the index. Because of this, a table can only have one clustered index, but it can have multiple non-clustered indexes.

The main difference between the two is that the database tries to keep the data in the same order as the corresponding keys in the clustered index. This can improve the performance of most query operations, as it provides a linear-access path to the data stored in the database.

### SQL Question 8: Calculate the Average Insurance Premium for Each Type of Insurance

Allstate is an insurance company offering various types of insurance such as auto, home, life, and renters. As an analyst, your task is to calculate the average premium for each type of insurance policy sold by Allstate in the year 2021.

##### Example Input:
735134501/12/2021Auto2100
850216403/22/2021Home1800
673398806/18/2021Life3000
755270009/26/2021Renters900
842742311/25/2021Auto2300

In this SQL query, we're selecting the and the average of for each type from the table where the year of the is 2021. Then, we're grouping the results by to find the average premium for each type of policy sold in 2021.

##### Example Output:
Auto2200
Home1800
Life3000
Renters900

This output means the average premium for auto policies sold in 2021 was $2200, for home policies it was$1800, for life policies it was $3000, and for renters policies it was$900.

### Preparing For The Allstate SQL Interview

The best way to prepare for a Allstate SQL interview is to practice, practice, practice. In addition to solving the above Allstate SQL interview questions, you should also solve the 200+ SQL questions on DataLemur which come from companies like Google, Uber, and Microsoft.

Each SQL question has multiple hints, fully explained answers along with a discussion board to see how others solved it and crucially, there is an online SQL code editor so you can right in the browser run your query and have it executed.

To prep for the Allstate SQL interview it is also wise to solve SQL problems from other insurance companies like:

Stay up-to-date on the latest news and announcements from Allstate and discover how they're shaping the future of insurance!

However, if your SQL query skills are weak, forget about diving straight into solving questions – refresh your SQL knowledge with this free SQL for Data Analytics course.

This tutorial covers SQL concepts such as SQL joins with practice exercises and LEAD window function – both of which come up often in SQL interviews at Allstate.

### Allstate Insurance Data Science Interview Tips

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

Besides SQL interview questions, the other topics to prepare for the Allstate Data Science Interview include:

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

To prepare for Allstate Data Science interviews read the book Ace the Data Science Interview because it's got: