SQL Joins (Inner, Left, Right and Full Join)
Last Updated : 21 Jun, 2025
SQL joins are fundamental tools for combining data from multiple tables in relational databases. Joins allow efficient data retrieval, which is essential for generating meaningful observations and solving complex business queries. Understanding SQL join types, such as INNER JOIN, LEFT JOIN, RIGHT JOIN, FULL JOIN, and NATURAL JOIN is important for working with relational databases.
Types of SQL Joins
An SQL JOIN clause is used to query and access data from multiple tables by establishing logical relationships between them. It can access data from multiple tables simultaneously using common key values shared across different tables. We can use SQL JOIN with multiple tables. It can also be combined with other clauses, with the most common use being paired with JOIN and WHERE clause to filter data during data retrieval. Let us visualize how each join type operates:
1. SQL INNER JOIN
The INNER JOIN keyword selects all rows from both the tables as long as the condition is satisfied. This keyword will create the result set by combining all rows from both the tables where the condition satisfies i.e value of the common field will be the same.
Syntax
SELECT table1.column1,table1.column2,table2.column1,.... FROM table1 INNER JOIN table2 ON table1.matching_column = table2.matching_column;
Note: We can also write JOIN instead of INNER JOIN. JOIN is same as INNER JOIN.
Example of INNER JOIN
Consider the two tables, Student and StudentCourse, which share a common column ROLL_NO. Using SQL JOINS, we can combine data from these tables based on their relationship, allowing us to retrieve meaningful information like student details along with their enrolled courses.
1. Student Table
2. StudentCourse Table
Let's look at the example of INNER JOIN clause, and understand it's working. This query will show the names and age of students enrolled in different courses.
Query:
SELECT StudentCourse.COURSE_ID, Student.NAME, Student.AGE FROM Student INNER JOIN StudentCourse ON Student.ROLL_NO = StudentCourse.ROLL_NO;
Output
2. SQL LEFT JOIN
A LEFT JOIN returns all rows from the left table, along with matching rows from the right table. If there is no match, NULL values are returned for columns from the right table. LEFT JOIN is also known as LEFT OUTER JOIN.
Syntax
SELECT table1.column1,table1.column2,table2.column1,....
FROM table1
LEFT JOIN table2
ON table1.matching_column = table2.matching_column;
Note: We can also use LEFT OUTER JOIN instead of LEFT JOIN, both are the same.
LEFT JOIN Example
In this example, the LEFT JOIN retrieves all rows from the Student table and the matching rows from the StudentCourse table based on the ROLL_NO column.
Query:
SELECT Student.NAME,StudentCourse.COURSE_ID FROM Student LEFT JOIN StudentCourse ON StudentCourse.ROLL_NO = Student.ROLL_NO;
Output
3. SQL RIGHT JOIN
RIGHT JOIN returns all the rows of the table on the right side of the join and matching rows for the table on the left side of the join. It is very similar to LEFT JOIN for the rows for which there is no matching row on the left side, the result-set will contain null. RIGHT JOIN is also known as RIGHT OUTER JOIN.
Syntax
SELECT table1.column1,table1.column2,table2.column1,....
FROM table1
RIGHT JOIN table2
ON table1.matching_column = table2.matching_column;
Key Terms
- table1: First table.
- table2: Second table
- matching_column: Column common to both the tables.
Note: We can also use RIGHT OUTER JOIN instead of RIGHT JOIN, both are the same
RIGHT JOIN Example
In this example, the RIGHT JOIN retrieves all rows from the StudentCourse table and the matching rows from the Student table based on the ROLL_NO column.
Query:
SELECT Student.NAME,StudentCourse.COURSE_ID FROM Student RIGHT JOIN StudentCourse ON StudentCourse.ROLL_NO = Student.ROLL_NO;
Output
4. SQL FULL JOIN
FULL JOIN creates the result-set by combining results of both LEFT JOIN and RIGHT JOIN. The result-set will contain all the rows from both tables. For the rows for which there is no matching, the result-set will contain NULL values.
Syntax
SELECT table1.column1,table1.column2,table2.column1,....
FROM table1
FULL JOIN table2
ON table1.matching_column = table2.matching_column;
Key Terms
- table1: First table.
- table2: Second table
- matching_column: Column common to both the tables.
FULL JOIN Example
This example demonstrates the use of a FULL JOIN, which combines the results of both LEFT JOIN and RIGHT JOIN. The query retrieves all rows from the Student and StudentCourse tables. If a record in one table does not have a matching record in the other table, the result set will include that record with NULL values for the missing fields
Query:
SELECT Student.NAME,StudentCourse.COURSE_ID FROM Student FULL JOIN StudentCourse ON StudentCourse.ROLL_NO = Student.ROLL_NO;
Output
NAME | COURSE_ID |
|---|
HARSH | 1 |
PRATIK | 2 |
RIYANKA | 2 |
DEEP | 3 |
SAPTARHI | 1 |
DHANRAJ | NULL |
ROHIT | NULL |
NIRAJ | NULL |
NULL | 4 |
NULL | 5 |
NULL | 4 |
5. SQL Natural Join (?)
Natural join can join tables based on the common columns in the tables being joined. A natural join returns all rows by matching values in common columns having same name and data type of columns and that column should be present in both tables.
- Both table must have at least one common column with same column name and same data type.
- The two table are joined using Cross join.
- DBMS will look for a common column with same name and data type. Tuples having exactly same values in common columns are kept in result.
Example:
Look at the two tables below- Employee and Department
Employee |
|---|
| Emp_id | Emp_name | Dept_id |
| 1 | Ram | 10 |
| 2 | Jon | 30 |
| 3 | Bob | 50 |
Department |
|---|
| Dept_id | Dept_name |
| 10 | IT |
| 30 | HR |
| 40 | TIS |
Find all Employees and their respective departments.
(Employee) ? (Department)
Output:
| Emp_id | Emp_name | Dept_id | Dept_id | Dept_name |
|---|
| 1 | Ram | 10 | 10 | IT |
| 2 | Jon | 30 | 30 | HR |
Conclusion
SQL joins are essential tools for anyone working with relational databases. Understanding the different types of joins in SQL, like INNER JOIN, LEFT OUTER JOIN, RIGHT JOIN, and FULL JOIN, allows us to combine and query data effectively. With the examples and syntax covered here, we should feel confident applying these SQL join types to our data to retrieve meaningful observations and manage complex queries with ease. Use these SQL join techniques to streamline our data handling and enhance our SQL skills.
Similar Reads
SQL for Data Science Mastering SQL (Structured Query Language) has become a fundamental skill for anyone pursuing a career in data science. As data plays an increasingly central role in business and technology, SQL has emerged as the most essential tool for managing and analyzing large datasets. Data scientists rely on
7 min read
Introduction to SQL
What is SQL?SQL was invented in the 1970s by IBM and was first commercially distributed by Oracle. The original name was SEQUEL (Structured English Query Language), later shortened to SQL. It is a standardized programming language used to manage, manipulate and interact with relational databases. It allow users
9 min read
Difference Between RDBMS and DBMSDatabase Management System (DBMS) is a software that is used to define, create, and maintain a database and provides controlled access to the data. Why is DBMS Required?Database management system, as the name suggests, is a management system that is used to manage the entire flow of data, i.e, the i
4 min read
Difference between SQL and NoSQLChoosing between SQL (Structured Query Language) and NoSQL (Not Only SQL) databases is a critical decision for developers, data engineers, and organizations looking to handle large datasets effectively. Both database types have their strengths and weaknesses, and understanding the key differences ca
6 min read
SQL Data TypesSQL Data Types are very important in relational databases. It ensures that data is stored efficiently and accurately. Data types define the type of value a column can hold, such as numbers, text, or dates. Understanding SQL Data Types is critical for database administrators, developers, and data ana
5 min read
SQL | DDL, DML, TCL and DCLData Definition Language (DDL), Data Manipulation Language (DML), Transaction Control Language (TCL), and Data Control Language (DCL) form the backbone of SQL. Each of these languages plays a critical role in defining, managing, and controlling data within a database system, ensuring both structural
6 min read
Setting Up the Environment
SQL Basics
Relational Model in DBMSThe Relational Model organizes data using tables (relations) consisting of rows and columns. Each column represents a specific attribute with a unique name, while each row holds data about a real-world entity or relationship. As a record-based model, it stores data in fixed-format records with defin
10 min read
SQL SELECT QueryThe SQL SELECT query is one of the most frequently used commands to retrieve data from a database. It allows users to access and extract specific records based on defined conditions, making it an essential tool for data management and analysis. In this article, we will learn about SQL SELECT stateme
4 min read
SQL Data TypesSQL Data Types are very important in relational databases. It ensures that data is stored efficiently and accurately. Data types define the type of value a column can hold, such as numbers, text, or dates. Understanding SQL Data Types is critical for database administrators, developers, and data ana
5 min read
SQL | WITH ClauseSQL queries can sometimes be complex, especially when you need to deal with multiple nested subqueries, aggregations, and joins. This is where the SQL WITH clause also known as Common Table Expressions (CTEs) comes in to make life easier. The WITH Clause is a powerful tool that simplifies complex SQ
6 min read
SQL | GROUP BYThe SQL GROUP BY clause is a powerful tool used to organize data into groups based on shared values in one or more columns. It is most often used with aggregate functions like SUM, COUNT, AVG, MIN and MAX to perform summary operations on each group, helping us extract meaningful analysis from large
5 min read
PHP | MySQL LIMIT ClauseIn MySQL the LIMIT clause is used with the SELECT statement to restrict the number of rows in the result set. The Limit Clause accepts one or two arguments which are offset and count.The value of both the parameters can be zero or positive integers. Offset:It is used to specify the offset of the fir
3 min read
SQL LIMIT ClauseThe LIMIT clause in SQL is used to control the number of rows returned in a query result. It is particularly useful when working with large datasets, allowing us to retrieve only the required number of rows for analysis or display. Whether we're looking to paginate results, find top records, or just
5 min read
SQL Distinct ClauseThe SQL DISTINCT keyword is used in queries to retrieve unique values from a database. It helps in eliminating duplicate records from the result set. It ensures that only unique entries are fetched. Whether you're analyzing datasets or performing data cleaning, the DISTINCT keyword is Important for
4 min read
SQL Operators
SQL Comparison OperatorsSQL Comparison Operators are used to compare two values and check if they meet the specific criteria. Some comparison operators are = Equal to, > Greater than , < Less than, etc. Comparison Operators in SQLThe below table shows all comparison operators in SQL : OperatorDescription=The SQL Equa
3 min read
SQL - Logical OperatorsSQL Logical Operators are essential tools used to test the truth of conditions in SQL queries. They return boolean values such as TRUE, FALSE, or UNKNOWN, making them invaluable for filtering, retrieving, or manipulating data. These operators allow developers to build complex queries by combining, n
9 min read
SQL | Arithmetic OperatorsPrerequisite: Basic Select statement, Insert into clause, Sql Create Clause, SQL Aliases We can use various Arithmetic Operators on the data stored in the tables. Arithmetic Operators are: + [Addition] - [Subtraction] / [Division] * [Multiplication] % [Modulus] Addition (+) : It is used to perform a
5 min read
SQL | String functionsSQL String Functions are powerful tools that allow us to manipulate, format, and extract specific parts of text data in our database. These functions are essential for tasks like cleaning up data, comparing strings, and combining text fields. Whether we're working with names, addresses, or any form
7 min read
SQL Wildcard CharactersSQL wildcard characters are powerful tools that enable advanced pattern matching in string data. They are especially useful when working with the LIKE and NOT LIKE operators, allowing for efficient searches based on partial matches or specific patterns. By using SQL wildcard characters, we can great
6 min read
SQL AND and OR OperatorsThe SQL AND and OR operators are used to filter data based on multiple conditions. These logical operators allow users to retrieve precise results from a database by combining various conditions in SELECT, INSERT, UPDATE, and DELETE statements.In this article, we'll learn the AND and OR operators, d
3 min read
SQL | Concatenation OperatorThe SQL concatenation operator (||) is a powerful feature that allows us to merge two or more strings into a single output. It is widely used to link columns, character strings, and literals in SQL queries. This operator makes it easier to format and present data in a user-friendly way, combining mu
3 min read
SQL | MINUS OperatorThe Minus Operator in SQL is used with two SELECT statements. The MINUS operator is used to subtract the result set obtained by first SELECT query from the result set obtained by second SELECT query. In simple words, we can say that MINUS operator will return only those rows which are unique in only
2 min read
SQL | DIVISIONDivision in SQL is typically required when you want to find out entities that are interacting with all entities of a set of different types of entities. The division operator is used when we have to evaluate queries that contain the keyword 'all'. When to Use the Division OperatorYou typically requi
4 min read
SQL NOT OperatorThe SQL NOT Operator is a logical operator used to negate or reverse the result of a condition in SQL queries. It is commonly used with the WHERE clause to filter records that do not meet a specified condition, helping you exclude certain values from your results.In this article, we will learn every
3 min read
SQL | BETWEEN & IN OperatorIn SQL, the BETWEEN and IN operators are widely used for filtering data based on specific criteria. The BETWEEN operator helps filter results within a specified range of values, such as numbers, dates, or text, while the IN operator filters results based on a specific list of values. Both operators
5 min read
Working with Data
SQL | WHERE ClauseThe SQL WHERE clause allows filtering of records in queries. Whether you are retrieving data, updating records, or deleting entries from a database, the WHERE clause plays an important role in defining which rows will be affected by the query. Without WHERE clause, SQL queries would return all rows
4 min read
SQL ORDER BYThe ORDER BY clause in SQL is a powerful feature used to sort query results in either ascending or descending order based on one or more columns. Whether you are presenting data to users or analyzing large datasets, sorting the results in a structured way is essential. In this article, we will explo
5 min read
SQL INSERT INTO StatementThe SQL INSERT INTO statement is one of the most essential commands for adding new data into a database table. Whether you are working with customer records, product details or user information, understanding and mastering this command is important for effective database management. How SQL INSERT I
6 min read
SQL UPDATE StatementIn SQL, the UPDATE statement is used to modify existing records in a table. Whether you are updating a single record or multiple records at once, SQL provides the necessary functionality to make these changes. Whether you are working with a small dataset or handling large-scale databases, the UPDATE
6 min read
SQL DELETE StatementThe SQL DELETE statement is an essential command in SQL used to remove one or more rows from a database table. Unlike the DROP statement, which removes the entire table, the DELETE statement removes data (rows) from the table retaining only the table structure, constraints, and schema. Whether you n
4 min read
SQL Data TypesSQL Data Types are very important in relational databases. It ensures that data is stored efficiently and accurately. Data types define the type of value a column can hold, such as numbers, text, or dates. Understanding SQL Data Types is critical for database administrators, developers, and data ana
5 min read
ALTER (RENAME) in SQLIn SQL, making structural changes to a database is often necessary. Whether it's renaming a table or a column, adding new columns, or modifying data types, the SQL ALTER TABLE command plays a critical role. This command provides flexibility to manage and adjust database schemas without affecting the
5 min read
SQL ALTER TABLEThe SQL ALTER TABLE statement is a powerful tool that allows you to modify the structure of an existing table in a database. Whether you are adding new columns, modifying existing ones, deleting columns or renaming them, the ALTER TABLE statement enables you to make changes without losing the data s
5 min read
SQL Queries
SQL | SubqueryIn SQL, subqueries are one of the most powerful and flexible tools for writing efficient queries. A subquery is essentially a query nested within another query, allowing users to perform operations that depend on the results of another query. This makes it invaluable for tasks such as filtering, cal
6 min read
Nested Queries in SQLA nested query (also called a subquery) is a query embedded within another SQL query. The result of the inner query is used by the outer query to perform additional operations. Subqueries can be used in various parts of an SQL query such as SELECT, FROM or WHERE Clauses. They are commonly used for p
7 min read
Joining Three or More Tables in SQLSQL joins are an essential part of relational database management, allowing users to combine data from multiple tables efficiently. When the required data is spread across different tables, joining these tables efficiently is necessary.In this article, we’ll cover everything we need to know about jo
5 min read
Inner Join vs Outer JoinInner Join and Outer Join are the types of join. The inner join has the work to return the common rows between the two tables, whereas the Outer Join has the work of returning the work of the inner join in addition to the rows that are not matched. Let's discuss both of them in detail in this articl
9 min read
SQL | Join (Cartesian Join & Self Join)In SQL, CARTESIAN JOIN (also known as CROSS JOIN) and SELF JOIN are two distinct types of joins that help combine rows from one or more tables based on certain conditions. While both joins may seem similar, they serve different purposes. Let’s explore both in detail.CARTESIAN JOINA Cartesian Join or
4 min read
How to Get the Names of the Table in SQLRetrieving table names in SQL is a common task that aids in effective database management and exploration. Whether we are dealing with a single database or multiple databases, knowing how to retrieve table names helps streamline operations. SQL provides the INFORMATION_SCHEMA.TABLES view, which offe
3 min read
SQL | SubqueryIn SQL, subqueries are one of the most powerful and flexible tools for writing efficient queries. A subquery is essentially a query nested within another query, allowing users to perform operations that depend on the results of another query. This makes it invaluable for tasks such as filtering, cal
6 min read
How to Fetch Duplicate Rows in a Table?Identifying duplicate rows in a database table is a common requirement, especially when dealing with large datasets. Duplicates can arise due to data entry errors, system migrations, or batch processing issues. In this article, we will explain efficient SQL techniques to identify and retrieve duplic
3 min read
Data Manipulation
SQL Joins (Inner, Left, Right and Full Join)SQL joins are fundamental tools for combining data from multiple tables in relational databases. Joins allow efficient data retrieval, which is essential for generating meaningful observations and solving complex business queries. Understanding SQL join types, such as INNER JOIN, LEFT JOIN, RIGHT JO
5 min read
SQL Inner JoinSQL INNER JOIN is a powerful and frequently used operation in relational databases. It allows us to combine two or more tables based on a related column, returning only the records that satisfy the join conditionThis article will explore the fundamentals of INNER JOIN, its syntax, practical examples
4 min read
SQL Outer JoinSQL Outer Joins allow retrieval of rows from two or more tables based on a related column. Unlike inner Joins, they also include rows that do not have a corresponding match in one or both of the tables. This capability makes Outer Joins extremely useful for comprehensive data analysis and reporting,
4 min read
SQL Self JoinA Self Join in SQL is a powerful technique that allows one to join a table with itself. This operation is helpful when you need to compare rows within the same table based on specific conditions. A Self Join is often used in scenarios where there is hierarchical or relational data within the same ta
3 min read
How to Group and Aggregate Data Using SQL?In SQL, grouping and aggregating data are essential techniques for analyzing datasets. When dealing with large volumes of data, we often need to summarize or categorize it into meaningful groups. The combination of the GROUP BY clause and aggregate functions like COUNT(), SUM(), AVG(), MIN(), and MA
4 min read
SQL HAVING Clause with ExamplesThe HAVING clause in SQL is used to filter query results based on aggregate functions. Unlike the WHERE clause, which filters individual rows before grouping, the HAVING clause filters groups of data after aggregation. It is commonly used with functions like SUM(), AVG(), COUNT(), MAX(), and MIN().
4 min read
Data Analysis
CTE in SQLIn SQL, a Common Table Expression (CTE) is an essential tool for simplifying complex queries and making them more readable. By defining temporary result sets that can be referenced multiple times, a CTE in SQL allows developers to break down complicated logic into manageable parts. CTEs help with hi
6 min read
Window Functions in SQLSQL window functions are essential for advanced data analysis and database management. It is a type of function that allows us to perform calculations across a specific set of rows related to the current row. These calculations happen within a defined window of data and they are particularly useful
6 min read
Pivot and Unpivot in SQLIn SQL, PIVOT and UNPIVOT are powerful operations used to transform data and make it more readable, efficient, and manageable. These operations allow us to manipulate tables by switching between rows and columns, which can be crucial for summarizing data, reporting, and data analysis. Understanding
4 min read
Data Preprocessing in Data MiningData preprocessing is the process of preparing raw data for analysis by cleaning and transforming it into a usable format. In data mining it refers to preparing raw data for mining by performing tasks like cleaning, transforming, and organizing it into a format suitable for mining algorithms. Goal i
6 min read
SQL Functions (Aggregate and Scalar Functions)SQL Functions are built-in programs that are used to perform different operations on the database. There are two types of functions in SQL: Aggregate FunctionsScalar FunctionsSQL Aggregate FunctionsSQL Aggregate Functions operate on a data group and return a singular output. They are mostly used wit
4 min read
MySQL Date and Time FunctionsHandling date and time data in MySQL is essential for many database operations, especially when it comes to handling timestamps, scheduling tasks, or generating time-based. MySQL provides a variety of date and time functions that help users work with date values, perform calculations, and format the
6 min read
SQL | Date Functions (Set-1)SQL Date Functions are essential for managing and manipulating date and time values in SQL databases. They provide tools to perform operations such as calculating date differences, retrieving current dates and times and formatting dates. From tracking sales trends to calculating project deadlines, w
5 min read
SQL | Date Functions (Set-2)SQL Date Functions are powerful tools that allow users to manipulate, extract , and format date and time values within SQL databases. These functions simplify handling temporal data, making them indispensable for tasks like calculating intervals, extracting year or month values, and formatting dates
5 min read
SQL | Numeric FunctionsSQL Numeric Functions are essential tools for performing mathematical and arithmetic operations on numeric data. These functions allow you to manipulate numbers, perform calculations, and aggregate data for reporting and analysis purposes. Understanding how to use SQL numeric functions is important
3 min read
SQL Aggregate functionsSQL Aggregate Functions are used to perform calculations on a set of rows and return a single value. These functions are particularly useful when we need to summarize, analyze, or group large datasets in SQL databases. Whether you are working with sales data, employee records or product inventories,
4 min read
Data Visualization