anti Join SQL | Oracle Anti Join - oracle tutorial - sql tutorial
What is Oracle Anti-join ?
- An anti-join, also called an excluding-join or left-outer-join, comes from requesting data from a table where some value is not in another table.
- Anti-join is used to make the queries run faster. It is a very powerful SQL construct Oracle offers for faster queries.
- Anti-join between two tables returns rows from the first table where no matches are found in the second table. It is opposite of a semi-join. An anti-join returns one copy of each row in the first table for which no match is found.
- Anti-joins are written using the NOT EXISTS or NOT IN constructs.
- Let's take two tables "departments" and "customer"