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328. COALESCE Function

Learn how to return the first non-NULL value from multiple expressions.

📘 Lesson 328 of 728 ⏱ 10 min 🎯 Intermediate

COALESCE evaluates expressions from left to right and returns the first value that is not NULL.

Real-world databases frequently contain missing values. COALESCE helps provide fallback values and create cleaner analytical results.

Display a customer's alternate phone number when the primary phone number is missing.

SQL 
SELECT
    CustomerName,
    COALESCE(PrimaryPhone, AlternatePhone, 'Not Available') AS ContactNumber
FROM Customers;

COALESCE is widely used for NULL handling, reporting, data preparation, financial calculations, and fallback values.

  • COALESCE handles NULL values.
  • It evaluates expressions from left to right.
  • It returns the first non-NULL value.
  • Multiple fallback values can be provided.
  • It is widely used in reporting.
What does COALESCE do?

COALESCE returns the first non-NULL value from a list of expressions.

Why is COALESCE useful for Data Analysts?

It allows analysts to handle missing values and provide meaningful fallback values in reports and calculations.

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