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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 Exercises17,557 Learners4450 XPSQL Server Developer TrackSQL Server for Database Administrators Track

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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

    Free

    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.

    Play Chapter Now
    Introduction
    50 xp
    Formatting - player BMI
    100 xp
    Commenting - player BMI
    100 xp
    Commenting - how many Kiwis in the NBA?
    100 xp
    Aliasing
    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.

    Play Chapter Now
    Filtering with WHERE
    50 xp
    Column does not exist
    100 xp
    Functions in WHERE
    100 xp
    Test your knowledge of WHERE
    50 xp
    Filtering with HAVING
    50 xp
    Row filtering with HAVING
    100 xp
    Filtering with WHERE and HAVING
    100 xp
    Test your knowledge of HAVING
    50 xp
    Interrogation after SELECT
    50 xp
    SELECT what you need
    100 xp
    Limit the rows with TOP
    100 xp
    Should I use ORDER BY?
    50 xp
    Managing duplicates
    50 xp
    Remove duplicates with DISTINCT()
    100 xp
    UNION and UNION ALL
    100 xp
    UNION or DISTINCT()?
    50 xp
  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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    Sub-queries
    50 xp
    Uncorrelated sub-query
    100 xp
    Correlated sub-query
    100 xp
    Sub-query vs INNER JOIN
    100 xp
    Presence and absence
    50 xp
    INTERSECT
    100 xp
    EXCEPT
    100 xp
    Interrogating with INTERSECT
    100 xp
    Alternative methods 1
    50 xp
    IN and EXISTS
    100 xp
    NOT IN and NOT EXISTS
    100 xp
    NOT IN with IS NOT NULL
    100 xp
    Alternative methods 2
    50 xp
    INNER JOIN
    100 xp
    Exclusive LEFT OUTER JOIN
    100 xp
    Test your knowledge
    50 xp
  4. 4

    Query performance tuning

    Students are introduced to how STATISTICS TIME, STATISTICS IO, indexes, and executions plans can be used in SQL Server to help analyze and tune query performance.

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    Time statistics
    50 xp
    STATISTICS TIME in queries
    100 xp
    STATISTICS TIME results
    50 xp
    Page read statistics
    50 xp
    STATISTICS IO: Example 1
    100 xp
    STATISTICS IO: Example 2
    100 xp
    STATISTICS IO comparison
    50 xp
    Indexes
    50 xp
    Test your knowledge of indexes
    50 xp
    Clustered index
    100 xp
    Execution plans
    50 xp
    Sort operator in execution plans
    100 xp
    Test your knowledge of execution plans
    50 xp
    Query performance tuning: final notes
    50 xp

In the following tracks

SQL Server DeveloperSQL Server for Database Administrators

Datasets

Orders datasetNBAPlayers datasetNBATeams datasetNBAPlayersStatistics dataset

Collaborators

Mona Khalil
Becca Robins
Marianna Lamnina

Prerequisites

Intermediate SQL Server
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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