| Lesson 7 || Reading non-correlated subqueries |
| Objective ||Identify non-correlated Subqueries in Oracle |
Identify non-correlated Subqueries in Oracle
- The body of the select statement simply select the username from dba_users
- Let us reverse the NOT IN condition from the prior query and change it to an IN Clause
- The second query is easier to understand, and it will run much faster
Non-Correlated Subquery Examples
Always replace a non-correlated subquery that has the IN condition with a standard table join.
The next lesson examines index range scans.