Semi-join is introduced in Oracle 8.0. It provides an efficient method of performing a WHERE EXISTS or WHERE IN sub-queries. A semi-join returns one copy of each row in first table for which at least one match is found in second table, there is no need of further scanning of the second table once a record is found.
SELECT *
Here the following is the...
How to Tune SQL with SEMI JOIN by Hints INDEX_DESC Injection for Oracle?
SELECT *
FROM DEPARTMENT
where dpt_idin (select emp_dept from EMPLOYEE
where emp_id >3300000)
Here the following is the...
How to Tune SQL with SEMI JOIN by Hints INDEX_DESC Injection for Oracle?