How can I do a FULL OUTER JOIN in MySQL?
Hello MaatD,
Using LEFT JOIN and RIGHT JOIN with UNION : MySQL does not support FULL OUTER JOIN directly, but you can achieve it by combining LEFT JOIN and RIGHT JOIN with UNION.
SELECT * FROM table1 LEFT JOIN table2 ON table1.id = table2.id UNION SELECT * FROM table1 RIGHT JOIN table2 ON table1.id = table2.id;
Explanation :
The first SELECT statement performs a LEFT JOIN to include all records from table1 and the matched records from table2. The second SELECT statement performs a RIGHT JOIN to include all records from table2 and the matched records from table1. The UNION operator combines the results of both SELECT statements, effectively simulating a FULL OUTER JOIN.
Hello MaatD,
Using Subqueries with NOT EXISTS : You can use subqueries to perform a FULL OUTER JOIN by including all rows from both tables that do not have matches in the other table.
SELECT * FROM table1 LEFT JOIN table2 ON table1.id = table2.id UNION SELECT * FROM table1 RIGHT JOIN table2 ON table1.id = table2.id WHERE table1.id IS NULL OR table2.id IS NULL;
Explanation:
The first SELECT statement performs a LEFT JOIN and includes all rows from table1 and the matched rows from table2. The second SELECT statement performs a RIGHT JOIN and includes all rows from table2 and the matched rows from table1. The WHERE clause ensures that only rows with unmatched id values (i.e., NULL values) are included, simulating a FULL OUTER JOIN.