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124. COALESCE Function

Learn how COALESCE can replace NULL values with an alternative value.

📘 Lesson 124 of 728 ⏱ 9 min 🎯 Intermediate

COALESCE returns the first non-NULL expression from a list of expressions. It is commonly used to provide fallback values when data is missing.

Business reports often need readable values instead of NULL. COALESCE allows analysts to handle missing information without changing the underlying data.

If a customer's phone number is NULL, the report can display 'Not Provided' instead.

SQL 
SELECT
    CustomerName,
    COALESCE(PhoneNumber, 'Not Provided') AS PhoneNumber
FROM Customers;

COALESCE is widely used in reporting, data transformation, customer analysis, financial reporting, and data cleaning.

  • COALESCE handles NULL values.
  • It returns the first non-NULL expression.
  • Multiple fallback values can be provided.
  • It is useful for reporting.
  • It can simplify NULL handling.
What does COALESCE do?

COALESCE returns the first non-NULL value from the expressions provided.

Why is COALESCE useful?

It allows missing values to be replaced with meaningful fallback values in query results.

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