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SQL SUM Function

Quick summary: The SQL SUM() function returns the total of a numeric column.

SQL SUM Syntax 

SELECT SUM(column_name) FROM table_name WHERE condition
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SQL SUM Basic examples 

SELECT SUM(total) FROM orders;
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Output:
Total order amount

Adds all numeric values.

SQL SUM Real-world usage 

SELECT SUM(total) FROM orders WHERE status = 'paid';
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Output:
Total revenue

Calculates business metrics.

SQL SUM Edge cases 

SELECT SUM(total) FROM orders WHERE status = 'canceled';
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Output:
NULL

Returns NULL when no rows match.

SQL SUM Common mistakes

Assuming SUM returns 0

SUM returns NULL if no rows match.

Incorrect
SUM(total)
Correct
COALESCE(SUM(total), 0)

Use COALESCE to handle NULL.

SQL SUM Frequently Asked Questions

What does SUM() do in SQL?

Calculates the total of a numeric column.

Use case of SUM()?

Total calculations.

Handles NULL?

Ignores NULL values.

Return type?

Numeric.

Common mistake?

Using on non-numeric data.

Works with GROUP BY?

Yes.

Supports DISTINCT?

Yes.

Performance?

Efficient.

Used in reports?

Yes.

Alternative?

Manual aggregation.

Handles negative numbers?

Yes.

Best practice?

Validate numeric input.

SQL SUM Related SQL Keywords