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150+ SQL Practice Exercises
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Articles
Cookbook
15 Nov 2018
Ignacio L. Bisso
How to Install PostgreSQL on Windows 10 in 5 Minutes
It may look like a complicated task to install PostgreSQL, Oracle, or SQL Server or any other database software, but it really isn’t! These days, most relational database management systems come with installation wizards that make the process much simpler. In this article, we’ll look at how to install PostgreSQL and test that the installation is working. Install PostgreSQL: Steps Involved To install PostgreSQL, we’ll complete the following tasks:
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8 Oct 2018
Dorota Wdzięczna
Microsoft SQL Server 2017 Installation Step by Step
Microsoft SQL Server is one of the most popular professional database servers on the market. In this guide, I’ll show you all SQL Server 2017 installation steps to help you install it on the Windows operating system together with SQL Management Studio. If you want to learn T-SQL, the dialect of SQL used in SQL Server, check out our SQL from A to Z in MS SQL Server track.
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27 Sep 2018
Ignacio L. Bisso
How to Begin Running SQL Queries
In this article, I’ll explain how to run a SQL query to help you execute your first one. Let’s jump right in! Running SQL queries for the first time is not a complex task, but it can seem intimidating at first if you’re a complete beginner. But once you get past that initial roadblock, you’ll be able to focus on learning SQL and writing more interesting queries to meet your business needs.
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14 Aug 2018
Aldo Zelen
SQL Indexing 101
Indexes are one of the most misused and misunderstood entities in physical database design. A good understanding of indexes and how they solve database performance problems is necessary for any database novice. In this article, we'll look at basic database indexes and their role in database development. To picture what an index is, consider a textbook. At the end of most textbooks is an index listing all the terms one can find in the text and the pages on which they appear.
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31 Jul 2018
Aldo Zelen
How to Use a SQL Wildcard
SQL wildcard allows us to filter data matching certain patterns in SQL. We use SQL wildcards with the LIKE operator in the WHERE clause of a query to filter data. In this beginner’s article, we’ll look at everything you need to know about basic SQL wildcards. If you like playing cards, then you know that wildcards can substitute any other card in your deck. Similarly, SQL wildcards can substitute one or more characters.
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18 Jul 2018
Aldo Zelen
SQL Filtering 101
Sometimes, SQL queries return lots of data you don't need. In this article, we'll look at a simple example of filtering SQL queries to reduce the complexity of your data. The key to learning how to filter data in SQL is understanding the very basics of Boolean algebra. That's just a fancy term mathematicians use to describe expressions involving logical values (true/false) and their associated operators (and, or, not, etc.
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6 Jul 2018
Kate Stolarek
Why Learn SQL Over the Summer
Think summer is reserved for flying to warm places and hanging out at the beach? Sure! But it's also a great time to learn new skills that you haven't had time for. If you recently graduated from high school and want to get a head start on computer programming for college, learning SQL over the summer is a great opportunity. You have nothing to lose and everything to gain—SQL is actually really easy to learn, especially with so much free time over the summer.
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8 Jun 2018
Ignacio L. Bisso
Improving Slow Query Performance: When Runtime Matters
As SQL users, we usually focus on writing queries that return correct results. However, there are more things to consider when you're writing a query; one of them is query performance. In this article, we'll look at some examples where query response time is critical. Scene One: 911 Call Center Let's suppose we're at a 911 call center, when the phone rings. One of the operators answers the call; a witness reports that a man has been shot.
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8 May 2018
Ignacio L. Bisso
Converting Subqueries to Joins
Not all queries are alike, especially in terms of performance. In this article, we'll look at how you can convert SQL subqueries to joins for improved efficiency. When Should I Use SQL Subqueries? Great question! Unfortunately, there's no concrete answer. SQL beginners tend to overuse subqueries. Typically, once they find that SQL construction works in one situation, they try to apply that same approach to other situations. It's only natural.
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17 Apr 2018
Aldo Zelen
Essential SQL Terms to Know for Beginners and Pros
Working with databases can seem daunting to a non-technical person. Right away, you’re bombarded with new terms that make your head spin. Database, database instance, table, SQL and others are some of the basic terms that you need to understand just to have a normal conversation with your technical colleagues. In this article, we’ll explore some basic SQL database terminology you need to know to succeed. Imagine you’re attending a meeting with the development staff and suddenly feel as if you’re listening to white noise.
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