Gain insights into SQL by exploring database creation, data manipulation, and advanced queries. Learn about practical applications and practice for SQL interviews to build confidence and readiness.

sql.tar.gz

The ability to work SQL is becoming an increasingly in-demand skill, both for software developers and people in less technical roles. If you’re interested in learning SQL and have no prior experience with it, then this course will be your light in a dark tunnel.

You’ll start by covering the basics of SQL such as how to create a database, how to insert, query, and update data. You’ll also learn fundamental concepts that developers and data scientists use everyday such as multi-table operations, nested queries, and how to set up views. 

Throughout, you’ll get to execute SQL queries in your browser and see results in real-time - you won’t need to worry about set-up.

At the end of this course, you’ll also get some hands-on practice with common SQL interview questions, so when the time comes, you’ll be ready and confident to answer any question that comes your way. Let’s get started!

An Introductory Guide to SQL

## Having Clause
We are familiar with the __WHERE__ clause that can be used to filter rows. In the same way, the __HAVING__ clause allows us to filter groups. At times, the __HAVING__ clause can be used to filter rows to display but that is not the intended use and can make the query slower. The __HAVING__ clause should be used to decide what rows form each group. Remember the __HAVING__ clause works on groups of rows whereas the __WHERE__ clause works on individual rows. We'll work with a couple of queries in this lesson to clarify the concept.

### Example Syntax
> SELECT **col1, AggregateFunction(col3) AS count** 
>
> FROM **table**
>
> GROUP BY **col1, col2, ... coln**
>
> HAVING **count > 75**
>
> ORDER BY **col2**;


>Connect to the terminal below by clicking in the widget. Once connected, the command line prompt will show up. Enter or copy and paste the command **./DataJek/Lessons/24lesson.sh** and wait for the MySQL prompt to start-up.

# Having Clause
We are familiar with the __WHERE__ clause that can be used to filter rows. In the same way, the __HAVING__ clause allows us to filter groups. At times, the __HAVING__ clause can be used to filter rows to display but that is not the intended use and can make the query slower. The __HAVING__ clause should be used to decide what rows form each group. Remember the __HAVING__ clause works on groups of rows whereas the __WHERE__ clause works on individual rows. We'll work with a couple of queries in this lesson to clarify the concept.

## Example Syntax
> SELECT **col1, AggregateFunction(col3) AS count** 
>
> FROM **table**
>
> GROUP BY **col1, col2, ... coln**
>
> HAVING **count > 75**
>
> ORDER BY **col2**;


>Connect to the terminal below by clicking in the widget. Once connected, the command line prompt will show up. Enter or copy and paste the command **./DataJek/Lessons/24lesson.sh** and wait for the MySQL prompt to start-up.

This lesson demonstrates how to use the HAVING clause.

Introduction

Basic SQL

Joins

Nested Queries

Multi Table Operations

Views

Stored Procedures

Triggers

Miscellaneous

Practice & Prep

Epilogue

HAVING

Having Clause

Example Syntax