SELECT and Joins

SQL Essentials and Basic CRUD read rows from one table. Real questions cross tables: which customers never ordered, what each order is worth, which category sits under which. This section answers them with the clauses of SELECT, the join types and the set operators, on a freshly loaded bookshop database. Sorting and paging are in ORDER BY and LIMIT.

Subsections

• SELECT Execution Order
• Projections and DISTINCT
• Filtering with WHERE
• GROUP BY, HAVING, and ROLLUP
• Cross Joins
• INNER JOIN and the ON Clause
• LEFT and RIGHT OUTER JOIN
• Self and Multi-Table Joins
• Emulating a FULL OUTER JOIN
• UNION, INTERSECT, and EXCEPT
• VALUES ROW()
• CASE, IF() and Pivots