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course

Improving Query Performance in SQL Server

Intermediate

4.2+

Updated 01/2025

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

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SQLProgramming4 hours16 videos58 exercises4,450 XP22,060Statement of Accomplishment

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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.

Prerequisites

Intermediate SQL Server

1

Introduction, Review and The Order of Things

Introduction

Formatting - player BMI

Commenting - player BMI

Commenting - how many Kiwis in the NBA?

Ambiguous column names

Aliasing - team BMI

Query order

Processing order

Syntax order - New Zealand earthquakes

Syntax order - Japan earthquakes

Syntax order - very large earthquakes

2

Filtering and Data Interrogation

Filtering with WHERE

Column does not exist

Functions in WHERE

Test your knowledge of WHERE

Filtering with HAVING

Row filtering with HAVING

Filtering with WHERE and HAVING

Test your knowledge of HAVING

Interrogation after SELECT

SELECT what you need

Limit the rows with TOP

Should I use ORDER BY?

Managing duplicates

Remove duplicates with DISTINCT()

UNION and UNION ALL

UNION or DISTINCT()?

3

Sub-queries and presence or absence

Sub-queries

Uncorrelated sub-query

Correlated sub-query

Sub-query vs INNER JOIN

Presence and absence

Interrogating with INTERSECT

Alternative methods 1

IN and EXISTS

NOT IN and NOT EXISTS

NOT IN with IS NOT NULL

Alternative methods 2

Exclusive LEFT OUTER JOIN

Test your knowledge

4

Query performance tuning

Time statistics

STATISTICS TIME in queries

STATISTICS TIME results

Page read statistics

STATISTICS IO: Example 1

STATISTICS IO: Example 2

STATISTICS IO comparison

Test your knowledge of indexes

Clustered index

Execution plans

Sort operator in execution plans

Test your knowledge of execution plans

Query performance tuning: final notes

Improving Query Performance in SQL Server

Course
Complete

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Included withPremium or Teams

Don’t just take our word for it

*4.2

from 14 reviews

57%

14%

29%

0%

0%

Highest to Lowest
Lowest to Highest
Most recent
Top reviews

Lyndon H.

12 months

An excellent presentation showing that good practices can result in more efficient queries and maintainable for the future.

Julie L.

about 1 year

Nice

Melvin A.

over 1 year

Right to the point. I was expecting something like that.

Jānis Š.

over 1 year

Got to know many new things.

Emilio F.

almost 2 years

This course clearly teaches how queries are executed, how we can see each step of the query and how much each step costs in performance, how and what to look for when trying to optimize queries.

"An excellent presentation showing that good practices can result in more efficient queries and maintainable for the future."

Lyndon H.

"Nice"

Julie L.

"Right to the point. I was expecting something like that."

Melvin A.

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