INNER JOIN: Matching Rows Across Two Tables
All lessons
- INNER JOIN: Matching Rows Across Two TablesFree
- Joins with WHERE, GROUP BY and ORDER BY Locked
- LEFT JOIN: Keeping Rows Without a Match Locked
- ON vs WHERE: The Filter That Cancels a LEFT JOIN Locked
- RIGHT and FULL OUTER JOIN: Reconciling Two Lists Locked
- One-to-Many Joins: Fan-Out and Double Counting Locked
- Joining Three Tables: Following the Key Path Locked
- Self-Joins: A Table Joined to Itself Locked
- CROSS JOIN and Range Joins Locked
- Scalar Subqueries: One Value Inside Another Query Locked
- IN and NOT IN Subqueries (and the NULL Trap) Locked
- Correlated Subqueries: Comparing Each Row With Its Own Group Locked
- EXISTS and NOT EXISTS: Semi-Joins and Anti-Joins Locked
- Derived Tables: Subqueries in FROM Locked
- CTEs: Building a Query Step by Step With WITH Locked
- CASE Expressions and Conditional Aggregation Locked
- UNION vs UNION ALL: Stacking Results Locked
- INTERSECT and EXCEPT: Comparing Two Results Locked
- Dates in Queries: Ranges, Differences and Dialects Locked
- Final Project: A Customer Segment Report Locked
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The SQL
SELECT o.order_id, c.name, o.amount
FROM orders AS o
INNER JOIN customers AS c
ON c.customer_id = o.customer_id;
SELECT c.customer_id, c.name,
SUM(o.amount) AS revenue
FROM orders AS o
JOIN customers AS c
ON c.customer_id = o.customer_id
GROUP BY c.customer_id, c.name;Write the join condition as `c.customer_id = o.customer_id` with aliases on both sides. A join without an ON condition pairs every row with every row.
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