Oracle SQL Joins: Display Data from Multiple Table

Display Data from Multiple Table

Cartesian -Products:

Without any joining condition return the value. Is called a cartesian product.

Example:

Select employees. employees_id, employees. last_name , employees.department_id,departments.department_id,departments.location_id from employees. department;

Equi_Joins:

One table to another table equally joins is called Equi_Joins.

Example:

Select employees. employees_id, employees. last_name , employees.department_id,departments.department_id,departments.location_id from employees. Department where employees.department_id = department.department_id;

Non Equi_Joins:

Too many tables join.

Example:

Select employees. employees_id, employees. last_name , employees.department_id,departments.department_id,departments.location_id from employees. Department

where employees.department_id

Between department.department_id and department.location_id;

Outer_Joins:

When we find with the null value.

Example:

Select employees. employees_id, employees. last_name , employees.department_id,departments.department_id,departments.location_id from employees. Department

where employees.department_id (+)= department.department_id;

Self_Join:

When Join same table that is called self_join .

Example:

Select worker.last_name || ‘work as’ || manager.last_name from employees worker , employees manager  where worker.manager_id =manager.employee_id;

Oracle SQL Joins