Category: SQL

Work with dates using NOW, DATE_ADD, DATE_FORMAT, and differences.

Use ROUND, CEIL, FLOOR, ABS, and arithmetic expressions.

Add numeric values with SUM().

Compute averages with AVG().

Find extremes with MIN and MAX.

Aggregate per group with GROUP BY.

Pattern-match strings with LIKE and wildcards % and _.

Test missing values correctly with IS NULL / IS NOT NULL.

Summarize data with COUNT, SUM, AVG, MIN, and MAX.

Count rows or non-null values with COUNT().