Join with Using clause

In this lesson we are going to study about Join with Using clause in a database.

Join with Using clause:

• Using clause is used to join the tables where the column in those tables shares a same name .
• Join operation carried out in these two table according to the values in these two columns.
• The columns listed the using clause cannot have any qualifier in the
  statement and it should not include the where clause .

     It means we can’t select the value of these two columns in output and we
can’t use these columns in where clause.

Example:
we are having two table DEPARTMENTS and EMPLOYEES with comman column department_id .So, we can join this two table with Using clause.

SQL:

select e.employee_id,e.last_name,d.location_id
from employees e join departments d
using (department_id)

OUTPUT:

 same result with equi join:

select  e.employee_id,
e.last_name,d.location_id
from employees e , departments d
where e.employee_id =d.department_id






NOTE:

• Do not use a table name or alias in referenced columns.
• The NATURAL JOIN and USING clause are mutually exclusive.

Related Article

• Join
• Cross Join
• Equi Join
• Non Equi Join 
• Self Join
• Natural Join
• Join with ON clause
• Outer Join. 

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