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Every piece of information should only appear once in a relational database. However, you may have data that is available in many tables that have connection with one another. It’s critical to understand them before delving into the distinctions between INNER JOIN vs OUTER JOIN in SQL queries. JOIN is the process of merging two or more tables into one. One unique kind of connection that has one or more main keys is a linked table. These keys may be column aliases or main keys.

Because it affects the quantity of data retrieved, it is critical to distinguish the difference between INNER JOIN and OUTER JOIN. Whereas OUTER JOIN never loses any data, making it suitable for reporting and analytics, INNER JOIN is appropriate when only the linked records are needed. With the use of straightforward examples, we will go into great depth on OUTER JOIN vs INNER JOIN, and their main distinctions in this blog.

So, keep reading and exploring to learn the inner vs OUTER JOIN SQL differences with examples in 2025.

What is a Join in SQL?

As we briefly discussed above, the JOIN operator allows you to merge related information in a variety of ways. Joins may be classified into two primary categories: INNER JOIN and OUTER JOIN in SQL.

Simply said, SQL joins are a method of combining data from two or more tables according to a shared field. There are two kinds of SQL joins.

An INNER JOIN will only retain data from both tables that are connected to one another (in the final table), which is the primary difference between INNER JOIN and OUTER JOIN. In contrast, an OUTER JOIN will retain data in the resultant table that is distinct to the other table in MySQL database. Let’s talk about both INNER JOIN vs OUTER JOIN concepts.

OUTER JOIN vs INNER JOIN: Understanding Both Joins

Let’s discuss what is INNER JOIN and OUTER JOIN in SQL before we discuss their differences.

What is an INNER JOIN with an Example?

INNER JOIN can retrieve data from two tables with the same ID.

According to an initial criterion, an INNER JOIN only returns the rows that match between the two tables. It uses the ON keyword in SQL to specify a common column between two tables, which is used to merge data from those tables. A row in one table won’t be included in the result set if it doesn’t match a row in the other table.

Returning the common rows and records across two tables is the main goal of an INNER JOIN in SQL. This new out-of-process will show the combined results of its search for matching and overlapping data in the tables.

An Example For INNER JOIN

Let’s look at a typical situation where there are two inner OUTER JOIN tables: quantity and product pricing. The product name is the logical column to link the tables on, as it is the common information between the two tables. Certain goods are shared by both tables, while others are exclusive to one and have no counterparts in the other.

Only goods that are common in both tables are returned by an INNER JOIN on goods.

Also Read: SQL vs MySQL: Making the Right Database Choice For You

What is an OUTER JOIN with an Example?

In addition to the records (or rows) that an INNER JOIN would yield, an SQL join OUTER JOIN additionally returns additional rows for which there is no matching record in the other table. It is the main point of our INNER JOIN vs OUTER JOIN comparison.

Three different kinds of OUTER JOINs exist:

• Left Join or Left OUTER JOIN
• Right Join or Right OUTER JOIN
• Full OUTER JOIN (or even Full Join)

The portion of the inner OUTER JOIN data that gets compared, aggregated, and returned is denoted by each of these outer connections. Because some data is shared and other is not, nulls will occasionally be generated throughout this procedure.

The capabilities of an INNER JOIN are expanded by the SQL join OUTER JOIN. They do this by returning both the matched and non-matched rows. To be more precise, they only return the matching rows from the subordinate (inner) tables and all the rows from the dominant (outer) table.

Note: The LEFT JOIN is the one that is essentially used in every version of SQL. However, this isn’t true for FULL JOIN and RIGHT JOIN, which aren’t supported by different SQL versions.

Let’s discuss the three types of OUTER JOIN with examples.

The LEFT OUTER JOIN

All of the data in Table 1 and all of the shared data (the inner portion of the Venn diagram example) will be returned by a left OUTER JOIN, while just the matching data from Table 2 will be returned by a right join.

Example of a Left Join

On the ‘left’ (Prices table) of our sample database are two goods, oranges and tomatoes, for which there is no matching record on the ‘right’ (Quantities table). These rows with a NULL in the Quantity column are part of the result available in a left join. In the INNER JOIN vs OUTER JOIN, the INNER JOIN and the remaining rows in the result are identical.

The Right OUTER JOIN

The data from Table 2 and all shared data are returned via a right OUTER JOIN, but only the equivalent data from Table 1—the left join—is returned.

Example of a Right Join

Like the left join example, a right OUTER JOIN yields all rows from the INNER JOIN as well as two rows from the ‘right’ (Quantities table) that don’t have corresponding entries on the left: broccoli and squash.

Full OUTER JOIN

The well-known MySQL database management system does not enable full OUTER JOINs, or full joins, which aggregate and return all of the data from multiple tables at a time, regardless of whether there is common information.

Basically, a full join is the duplication of all the requested data in a single database as opposed to several tables. Nulls will be generated in cases when matching data is absent.

These are only the fundamentals; joins may become excess in use for a lot more. Some joins even have the ability to exclude other joins!

Also Read: What is MySQL Trigger: How To Create It?

INNER JOIN vs OUTER JOIN: Comparison Table

Here is the INNER JOIN vs OUTER JOIN comparison table:

There is no output of those entries that do not match the entries of another table.If entries of one table do not have any identical entries with another table, then you will get null values.If a related data entry is necessary as per the customer condition or database design, the INNER JOIN is optional.If a related data entry is not necessary as per the customer requirement or database strategy, then the OUTER JOIN is more appropriate.

INNER JOIN	OUTER JOIN
Recover data only if there is a match among the tables.	Recover all the data, even if there is no match.
It will not return NULL ideals.	In Full & Right OUTER JOINs, the data will be recovered as NULL standards if there is no data in any of the particular tables.
INNER JOIN does not have any type.	OUTER JOIN has three kinds: Left-OUTER JOIN, Right-OUTER JOIN, and Full-OUTER JOIN.
The process will become faster because it only returns corresponding values.	The process will become sluggish because it needs to handle NULL values.
The results given by the INNER JOIN have the fewest accesses and will be able to update the user necessities.	As you know, OUTER JOIN has dissimilar options such as left, right, and full join, so its procedure must be monitored and checked thoroughly.
You can perceive the lack of performance since SQL INNER JOIN is slower.	OUTER JOINs, particularly left OUTER JOINs, are quicker and provide better performance in most cases.
The gratification of the INNER JOIN condition is mandatory.	There are no circumstances that we have to see in the OUTER JOIN query necessarily.
It is a simple process in which the matching entries have no consideration for the left or right tables.	In OUTER JOIN between INNER JOIN vs OUTER JOIN, when the entries have a match, it will check whether either ailment is available for the left or right tables. Moreover, the entry has measures accordingly, except for full OUTER JOIN.

Investigating SQL Joins in More Depth

Understanding how SQL joins affect performance is another essential aspect of the idea. Choosing between INNER JOIN vs OUTER JOIN might affect query performance, especially when working with large datasets. INNER JOIN is usually quicker since it only provides rows with matching values in both tables, which results in a smaller result set. However, OUTER JOIN procedures may use more resources since they have to process and return mismatched entries, which expands the size of the result set.

You must also consider the specific use case while choosing a join type.

LEFT OUTER JOIN, for instance, is useful when you must include every left table entry regardless of whether there is a match in the right table. This is commonly popular in scenarios when it is necessary to show every object combiniton with any potential relationships, like when creating reports. FULL OUTER JOIN rarely comes into play, although it might be useful for complex queries that need the whole dataset from both tables, including non-matched entries.

When to Use SQL INNER JOIN vs OUTER JOIN 

The actual applications of INNER JOIN vs OUTER JOIN in data retrieval also vary.

When To Use THE INNER JOIN

When you just require the intersecting data from two tables, an INNER JOIN works well. If there are matching entries in both the product and sales databases, for instance, you may use INNER JOIN to locate goods that have been sold.

When To Use an OUTSIDE JOIN

When you want to return the whole dataset, including rows that aren’t corresponding, you should use an outside join. For instance, when creating a report that displays all departments, including those without workers, or all employees, including those without a department assignment.

Conclusion

Two of the most popular join families in SQL are INNER JOIN vs OUTER JOIN. Understanding their distinctions and unique applications distinguishes a SQL novice from an expert. If you select the incorrect join type, your supervisor will become furious with you. Moreover, the results will become totally inaccurate.

Additionally, while both INNER JOIN and OUTER JOIN in SQL may result in short-term data expenses, the former is more costly due to the increased risk of data loss. Database traffic may temporarily drop as a result of an OUTER JOIN. However,  it will swiftly return to its previous level when it will recover all tha data.

FAQs (Frequently Asked Questions)

What Is The Difference Between INNER And OUTER JOIN?

OUTER JOIN contains incompatible rows with NULLs filling in the gaps when there is no relevant data in it. On the other hand, INNER JOIN only provides matching rows from both tables.

When Should I Use INNER JOIN In SQL?

You should use INNER JOIN when you want to retrieve data from two or more tables with matching values in it.

When To Use OUTER JOIN In SQL?

When you need to extract every entry from one or both of the tables involved in the join—even if the other table has no matching rows—you use an outside join in SQL. An INNER JOIN, on the other hand, only returns rows if there is a match in both tables.

What Is The Difference Between INNER JOIN OUTER JOIN And CROSS JOIN?

You can combine data from two or more tables using SQL’s INNER JOIN vs OUTER JOIN, and CROSS JOIN functions. INNER JOIN can return the only the rows that match in both tables according to a certain criterion. All rows from at least one table and matching rows from the other tables have returned through an OUTER JOIN. All feasible row combinations from both tables have returned via a cross join.