SQL GROUP BY Guide - Essential SQL

GROUP BY SQL Queries to Summarize and Rollup Sets of Records

Group By in SQL Server with CUBE, ROLLUP and GROUPING SETS Examples

Using aggregate functions to manipulate the data - SQL Video Tutorial | LinkedIn Learning, formerly Lynda.com

SQL percentage calculation examples in SQL Server

Calculate SQL Percentile using the PERCENT_RANK function in SQL Server

SQL AVG() function introduction and examples

SQL con SELECT COUNT, SUM, AVG lista de ejemplos

SQL COUNT and SQL COUNT_BIG Functions