Hey Ninjas! As we all know, the Database is used to store information in the form of tables. And in MNCs, there are n numbers of tables in their databases. So have you ever thought about how these tables are being handled? If not, you are at the right place. Let's dive deep into this topic.
This blog will discuss the difference between equi join and natural join. But before moving to the main topic, let's first understand equi and natural join.
A join that is formed as a result of the equality condition between the two same columns of multiple tables is called an Equi join. This is also known as simple join. The comparison operator to denote the equi join is "=".
Syntax
The syntax of Equi join is as follows:
SELECT columnName (s)
FROM tableName1, tableName2, ...., tableNameN
WHERE tableName1.columnName = tableName2.columnName;
OR
SELECT columnName (s)
FROM tableName1
JOIN tableName2
ON tableName1.columnName = tableName2.columnName;
Example
Let's take an example of this for better understanding. Suppose we have two tables named Student and Marks, as shown below.
Student Table:
Marks Table:
As you can see, the RollNo column is the same in both tables, so by following the syntax of equi join, we have
SELECT * FROM Student, Marks WHERE Student.RollNo = Marks.RollNo;
Output:
The output remains the same even if we use the other syntax. Let's have a look.
SELECT * FROM Student JOIN Marks ON Student.RollNo = Marks.RollNo;
Output:
If you notice in this example, the RollNo column is rendering twice because the equi join just merged both tables on the basis of the RollNo. To overcome this, we have the Natural Join. Let's have a look.
Natural Join
A natural join is a kind of equi join that occurs when a common column with the same name in a different table gets compared and appears only once in the output.
Syntax
The syntax of Natural join is as follows:
SELECT columnName (s)
FROM tableName1
NATURAL JOIN tableName2;
Example
Let's take an example of this for better understanding. Suppose we have two tables that we used earlier, named Student and Marks, as shown below.
Student Table:
Marks Table:
The above tables have a common column, i.e., RollNo. So, we will use the natural join using this column (RollNo). Let's have a look.
SELECT * FROM Student NATURAL JOIN Marks;
Output:
Explanation: As you can see in the output, the column with the name RollNo. is the same in both the Student and Marks table but still, it occurred only once in the output after using the Natural Join.
Equi Join Vs Natural Join
As we are done with the definitions and working examples, it's time for the 1v1 comparison between equi and natural join. Let's check this in a tabular form.
Equi Join
Natural Join
Equi Join is a join having a condition where we use an equal operator.
While performing a natural join, we do not use an equal operator.
We use Equi Join if we need both tables in the output without missing any column.
We use Natural Join if we need only the unique columns without repetition.
We can use the WHERE clause or the ON clause in Equi join.
Just use the keyword NATURAL JOIN to perform the task.
The common column comes twice if we select all columns in the query.
The common column comes only once, even if we select all columns in the query.
The syntax of Equi Join is
SELECT columnName (s) FROM tableName (s) WHERE tableName1.columnName = tableName2.columnName;
The syntax of Natural Join is
SELECT columnName (s) FROM tableName1 NATURAL JOIN tableName2;
The four types of joins are Inner Join, Outer Join, Left Join (Left Outer Join), and Right Join (Right Outer Join).
Can we join the table by itself? If Yes, how?
Using Self-Joins, a table can be joined to itself in a self-join.
What are the basic types of joins?
There are two basic types of joins in SQL, Joins using Operators and Joins using Concepts. Joins using Operators include EQUI Join and Non-EQUI Join. And, Joins using Concepts include Inner Join, Outer Join, etc.
What is the main difference between the UNION and the UNION ALL clauses?
The Union extracts the rows specified in the query is the main difference between UNION and UNION ALL.
What is the importance of Joins in DBMS?
Joins are important in DBMS because they allow us to extract meaningful information by combining related data tables.
Conclusion
This article discusses the difference between Equi Join and Natural Join in detail. We have seen the definition, syntax, and example of Equi Join and Natural Join. Along with this, we have seen a comparison between Equi Join and Natural Join in tabular form.
We hope this blog has helped you enhance your knowledge of the difference between Equi Join and Natural Join. If you want to learn more, then check out our articles.
But suppose you have just started your learning process and are looking for questions from tech giants like Amazon, Microsoft, Uber, etc. In that case, you must look at the problems, interview experiences, and interview bundles for placement preparations.
However, you may consider our paid courses to give your career an edge over others!
8+ registered 