January 2020
Beginner
256 pages
5h 11m
English
Content preview from Sams Teach Yourself SQL in 10 Minutes a Day, 5th Edition
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Lesson 9. Summarizing Data
In this lesson, you will learn what the SQL aggregate functions are and how to use them to summarize table data.
Using Aggregate Functions
It is often necessary to summarize data without actually retrieving it all, and SQL provides special functions for this purpose. Using these functions, SQL queries are often used to retrieve data for analysis and reporting purposes. Examples of this type of retrieval are
Determining the number of rows in a table (or the number of rows that meet some condition or contain a specific value)
Obtaining the sum of a set of rows in a table
Finding the highest, lowest, and average values ...
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