Beginner

85. COALESCE Function

Learn how to replace NULL values with an alternative value using COALESCE.

📘 Lesson 85 of 728 ⏱ 8 min 🎯 Beginner

COALESCE returns the first non-NULL expression from a list of expressions. It is commonly used to provide a default value when a database column contains NULL.

Missing values can make reports difficult to read. COALESCE allows analysts to replace NULL with a meaningful default such as 'Not Available', zero, or another value.

If an employee does not have a manager assigned, COALESCE can display 'No Manager' instead of NULL.

SQL 
SELECT
    EmployeeName,
    COALESCE(ManagerName, 'No Manager') AS Manager
FROM Employees;

COALESCE is useful in reporting, data preparation, customer analysis, financial reporting, and dashboard datasets.

  • COALESCE returns the first non-NULL value.
  • It can replace NULL with a default value.
  • It can accept multiple expressions.
  • It is useful for cleaner reports.
  • It is commonly used in data transformation.
What does COALESCE do?

COALESCE returns the first non-NULL expression from the provided list.

Why is COALESCE useful?

It allows NULL values to be replaced with meaningful default values in queries and reports.

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