WHERE clause filters rows returned by SELECT, UPDATE, or DELETE statements. Tutorial uses university database schema with student, courses, and departments tables. Techniques work across MySQL, SQL Server, and PostgreSQL
SQL joins bring together data from multiple tables in a single query. Tables contain rows of similar or related data. Joins are performed using the JOIN keyword
WHERE clause filters rows in SELECT, UPDATE and DELETE statements. Arguments evaluate to true or false for each row. Multiple arguments can be combined using AND and OR operators
ORDER BY clause sorts table rows based on one or more columns. ORDER BY 1 sorts by first column in SELECT list. Default sorting is ascending (lowest to highest)
WHERE and HAVING clauses are fundamental to SQL SELECT command. Both clauses act as filters to remove records that don't meet criteria. WHERE filters at record level, HAVING filters at group level
WHERE clause filters datasets based on specified criteria. Multiple filters can be combined using AND operator. WHERE clause must come before GROUP BY in queries