Final answer:
Non-equality joins in SQL can be performed using the WHERE clause or the ON clause within a JOIN statement, where columns from different tables are compared using operators such as != or <>. These types of joins are useful for finding non-matching rows between tables.
Step-by-step explanation:
The syntax for a non-equality join in SQL can be specified in two ways; using the WHERE clause or the ON clause. A non-equality join is a join that uses comparison operators other than the equal sign (!= or <>) to compare columns from different tables.
Using the WHERE clause, you might write a query like this:
SELECT table1.column1, table2.column2
FROM table1, table2
WHERE table1.columnX <> table2.columnY;
When using the ON clause, which is typically used with joins like INNER JOIN, LEFT JOIN, or RIGHT JOIN, the syntax would look like this:
SELECT table1.column1, table2.column2
FROM table1
JOIN table2
ON table1.columnX <> table2.columnY;
In both methods, the key idea is that the join is based on a condition that specifies that the column values should not be equal. This approach is often used in scenarios where you want to find rows in one table that do not have corresponding rows in another table based on a specific column comparison.