You can now remove duplicates with DISTINCT and count unique values with COUNT DISTINCT, essential for accurate data analysis and reporting.

List unique departments with DISTINCT

Count unique customers with COUNT DISTINCT

Find unique department-job combinations

Compare COUNT(*) vs COUNT(DISTINCT)

Use DISTINCT with ORDER BY

ROLLUP, CUBE, and GROUPING SETS will teach you hierarchical aggregations with subtotals and grand totals for multi-dimensional analysis.