SQL is the most popular data analytics and data storage tool. We'll learn about the different types of SQL questions asked on interviews and how to approach them. 

SQL Interview

Why is SQL so Important?

Overview

How often does SQL show up in interviews?

SQL learning path overview

How to approach SQL questions

Introduction to SQL

Starting with the basics in SQL syntax and writing queries. What does SELECT do? How do you write a full SQL Query? How do we filter down a table and return different columns?

Introduction to Beginner SQL Questions

SELECT and WHERE

Select All Flights

Like Tracker

SELECTive Wine Connoisseur

Aggregate Functions

Total Salary

Emails Opened

Beginner SQL Questions

Get started on tackling easy level SQL questions involving aggregations, joining multiple tables, and pulling data for beginning analytical reports.

Introduction to Easy SQL questions

SQL JOINs

Download Facts

GROUP BY and HAVING

Total Spent On Products

Largest Salary By Department

ORDER BY and LIMIT

Average Quantity

Miscellaneous Functions and Clauses

Manager Team Sizes

Session Difference

Top 5 Turnover Risk

Easy SQL Questions

SQL interviews have certain regularities. There are types of questions that appear often and common evaluation styles. This course provides useful tips to tackle most SQL interview questions.

Mastering the SQL Interview 

Tackling SQL Interview Questions

Types of SQL Interview Questions

SQL Interview Tips

Medium level SQL questions utilize more advanced concepts like sub-queries, window functions, and solving case study problems.

Introduction to medium SQL questions

DATETIME

Self-JOINs and CROSS JOINs

Subqueries and CTEs

Daily Logins

Employee Salaries (ETL Error)

Slacking Employees Salaries

CASE clause

Exam Scores

Customer Orders

Employee Salaries (Top 3 departments)

Handling NULL values

Empty Neighborhoods

Distance Traveled

LIKE and other useful functions

Window Functions

Last Transaction

Top Three Salaries

User Experience Percentage

Medium SQL Questions

Let's tackle advanced SQL interview questions that focus on multi-joins and layers of data interpretation. These questions may come up in take-home challenges and senior level interviews.

Introduction to hard SQL questions

Swipe Precision

Cumulative Distribution

Rolling Bank Transactions

Subscription Overlap

First Touch Attribution

Search CTR

Paired Products

Payments Received

Hard SQL Questions

SQL tests your analytical sense, ability to pull data for building models, and interpretation of datasets and metrics.

Brush up on your SQL skills and learn advanced tips and tricks

<p>Given two tables:  <code>accounts</code>, and <code>downloads</code>, find the average number of downloads for free vs paying accounts, broken down by day.</p>

<p><em>Note: You only need to consider accounts that have had at least one download before when calculating the average.</em></p>

<p><em>Note: round <code>average_downloads</code> to 2 decimal places.</em></p>

<p><strong>Example:</strong></p>

<p><strong>Input:</strong></p>

<p><code>accounts</code> table</p>

<table>
<thead>
<tr>
<th>Column</th>
<th>Type</th>
</tr>
</thead>

<tbody>
<tr>
<td><code>account_id</code></td>
<td>INTEGER</td>
</tr>

<tr>
<td><code>paying_customer</code></td>
<td>BOOLEAN</td>
</tr>
</tbody>
</table>
<p><code>downloads</code> table</p>

<table>
<thead>
<tr>
<th>column</th>
<th>type</th>
</tr>
</thead>

<tbody>
<tr>
<td><code>account_id</code></td>
<td>INTEGER</td>
</tr>

<tr>
<td><code>download_date</code></td>
<td>DATETIME</td>
</tr>

<tr>
<td><code>downloads</code></td>
<td>INTEGER</td>
</tr>
</tbody>
</table>
<p><strong>Output:</strong></p>

<table>
<thead>
<tr>
<th>Column</th>
<th>Type</th>
</tr>
</thead>

<tbody>
<tr>
<td><code>download_date</code></td>
<td>DATETIME</td>
</tr>

<tr>
<td><code>paying_customer</code></td>
<td>BOOLEAN</td>
</tr>

<tr>
<td><code>average_downloads</code></td>
<td>FLOAT</td>
</tr>
</tbody>
</table>


SQL Interview

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