Joins Vs Sub Queries In SQL

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Let's Clarify on this.

There is a lot of confusion about when to use Joins and when to use Sub-Queries in SQL. Are they alternatives to each other or are they different? Understanding & learning this is important as both concepts are the backbone of SQL. There are certain differences between Joins & Sub Queries in SQL. If you want to do advanced-level analysis & write down the queries accordingly then you need this clarification for sure.

Difference between Joins & Sub Queries in SQL

In this blog, we have covered whatever is required to answer these questions. Enjoy the good read!

S. No.CriteriaJoinsSub-Queries
1

Definition

A Join is a concept used to fetch rows from two or more tables based on a related column or set of columns.A Subquery (Nested Query) is a query that is embedded within another SQL query. This is also a technique to fetch data from multiple tables.
2

Use Case

Joins are especially useful with normalized databases, where data is stored in separate tables to reduce redundancy and maintain data integrity.Subqueries are used to fetch data based on the results of another or inner query. The result of another or inner query can be a single value or a temporary table.
3

Syntax Requirement

The syntax for a Join involves specifying the tables to be joined, the Join type, and the condition (common column) on which the tables are related.Subqueries can be used with various SQL commands like SELECT, INSERT, UPDATE, and DELETE.
4

Types

Inner, Outer, Cross, SelfSingle Row, Multi-Row, Multi-Column, Correlated
5

When to use

When you want to retrieve data in a single result set efficiently. This is a more optimized way as compared to Sub-queries.When the logic cannot be efficiently expressed using Joins alone. This is a less optimized way as compared to Joins.
6

Advantage

Joins help with a clear and concise way to retrieve data without the need for additional filtering or processing.Subqueries help us to perform complex filtering and calculations based on the results of the inner query.
7

Limitation

While Joins work well for combining data from different tables, they may not be suitable for certain complex data manipulations.Subqueries may make the SQL code more complex and harder to read.
8

Which one to use with Large Dataset

Joins are efficient when dealing with large datasets.Can be used with large datasets but TAT is high.

Conclusion

So now we know that Joins & Sub Queries in SQL are alternatives to each other and not different. The only point is that we need to use the correct one depending on the requirements & data.

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