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491. EQUI JOIN

Understand how an EQUI JOIN matches records using equality between related columns.

📘 Lesson 491 of 728 ⏱ 11 min 🎯 Intermediate

An EQUI JOIN is a JOIN where the matching condition uses the equality operator (=) between columns from two tables.

Most common SQL relationships are based on matching key values, making EQUI JOINs fundamental to relational data analysis.

Match employees with their departments using DepartmentID.

SQL 
SELECT
    e.EmployeeName,
    d.DepartmentName
FROM Employees e
INNER JOIN Departments d
    ON e.DepartmentID = d.DepartmentID;

Used extensively in employee, customer, sales, banking, inventory, and transaction databases.

  • EQUI JOIN uses the equality operator.
  • It commonly matches primary and foreign keys.
  • INNER JOIN is frequently implemented as an EQUI JOIN.
  • It is one of the most common JOIN patterns.
  • Correct key matching is essential.
What is an EQUI JOIN?

An EQUI JOIN matches rows from tables using an equality condition between columns.

What operator is used in an EQUI JOIN?

The equality operator (=) is used.

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