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Improving Query Performance in SQL Server

In this course, students will learn to write queries that are both efficient and easy to read and understand.

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4 Hours16 Videos58 Exercises13,181 Learners
4450 XP

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Course Description

A mission critical assignment is depending on your SQL coding skills. You’ve been given some code to fix. It is giving the results you need but it’s running too slow, and it’s poorly formatted making it hard to read. The deadline is tomorrow. You’ll need to reformat the code and try different methods to improve performance. The pressure is on!!! In this course we’ll be using SQL on real world datasets, from sports and geoscience, to look at good coding practices and different ways how we can can improve the performance of queries to achieve the same outcome.

  1. 1

    Introduction, Review and The Order of Things


    In this chapter, students will learn how SQL code formatting, commenting, and aliasing is used to make queries easy to read and understand. Students will also be introduced to query processing order in the database versus the order of the SQL syntax in a query.

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    50 xp
    Formatting - player BMI
    100 xp
    Commenting - player BMI
    100 xp
    Commenting - how many Kiwis in the NBA?
    100 xp
    50 xp
    Ambiguous column names
    50 xp
    Aliasing - team BMI
    100 xp
    Query order
    50 xp
    Processing order
    50 xp
    Syntax order - New Zealand earthquakes
    100 xp
    Syntax order - Japan earthquakes
    100 xp
    Syntax order - very large earthquakes
    100 xp
  2. 2

    Filtering and Data Interrogation

    This chapter introduces filtering with WHERE and HAVING and some best practices for how (and how not) to use these keywords. Next, it explains the methods used to interrogate data and the effects these may have on performance. Finally, the chapter goes over the roles of DISTINCT() and UNION in removing duplicates and their potential effects on performance.

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  3. 3

    Sub-queries and presence or absence

    This chapter is an introduction to sub-queries and their potential impacts on query performance. It also examines the different methods used to determine if the data in one table is present, or absent, in a related table.

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In the following tracks

Data AnalystSQL Server for Database Administrators


Becca RobinsMona KhalilMarianna Lamnina
Dean Smith Headshot

Dean Smith

Founder, Atamai Analytics

Dean Smith is geoscientist specializing in information management systems for mining and mineral exploration. He has more than ten years of experience working with SQL Server and data visualization. Dean is the founder of Atamai Analytics, which provides information management and data analytics consulting services to the mining and mineral exploration communities.
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