• Learning MySQL By Example
  • Introduction
  • 1. How to Retrieve Data From a Single Table
  • 2. How to Retrieve Data from Multiple Tables
  • 3. Using Functions
  • 4. How to Insert, Update, Delete Data in Tables
  • 5. Summary Queries and Aggregate Functions
  • 6. Working With Subqueries
  • 7. SQL Views
  • 8. SQL Indexes
  • Glossary
  • Index
  • Download
  • Translations
  • 5.7

    Using the DISTINCT Statement

    Removing Duplicate Values With DISTINCT

    • The DISTINCT keyword allows you to eliminate duplicate rows in aggregate functions.
    • You may also use the DISTINCT keyword with columns of the base table in a SELECT statement.
    • COUNT(list_price) counts all the rows in the product table that have a list price.
    • COUNT(DISTINCT list_price) eliminates duplicate values in the list_price.

    Code Sample:

    Example
    USE bike;
    SELECT COUNT(list_price), COUNT(DISTINCT list_price) 
    FROM product;

    Output:

    ag_07.png

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