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SQL USING Clause

SQL | USING Clause: In this tutorial, we are going to learn about the USING clause with its usages, syntax and query examples in SQL (Structured Query Language).
Submitted by Abhishek Goel, on April 05, 2020

SQL | USING Clause

On the off chance that few sections have similar names however the datatypes don't coordinate, the NATURAL JOIN statement can be altered with the USING condition to determine the segments that ought to be utilized for an EQUIJOIN.

• USING Clause is utilized to coordinate just a single section when more than one segment matches.
• Regular JOIN and USING Clause are unrelated.
• It ought not to have a qualifier(table name or Alias) in the referenced segments.
• Regular JOIN utilizes all the segments with coordinating names and datatypes to join the tables. The USING Clause can be utilized to determine just those segments that ought to be utilized for an EQUIJOIN.

Syntax:

    SELECT <table_name>.<column_name> AS <column_name> 
    FROM <table_name> JOIN <table_name> USING (<column_name>);

Example:

Here we will be considering the following two tables,

Table: PETS

PETID	ANIMAL	NAME	OWNERID
11	Dog	Rocky	23
22	Cat	Charles	34
33	Mouse	Mickey	23
44	Parrot	Honey	56
55	Rabbit	Smudge	34
66	Hamster	Fluffy	56

Table: Owner

OWNERID	NAME
23	Tina
34	Tarun
56	Sammy

Query: To Know the names of the owners of the pet.

SELECT Owner.name AS owners, PETS.name AS pet, PETS.Animal 
FROM Owner JOIN PETS USING (ownerid);

Output:

OWNERS	PET	ANIMAL
Tina	Rocky	Dog
Tarun	Charles	Cat
Tina	Mickey	Mouse
Sammy	Honey	Parrot
Tarun	Smudge	Rabbit
Sammy	Fluffy	Hamster

Note: At the point when we utilize the USING proviso in a join explanation, the join section isn't qualified with table Alias. Don't Alias it regardless of whether a similar segment is utilized somewhere else in the SQL explanation.

You can also enroll in an SQL certification course to learn more about writing queries with clause.