A data analyst wants to skip null values in calculations and return non-null values for one or more fields. Which SQL function helps with this?

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Multiple Choice

A data analyst wants to skip null values in calculations and return non-null values for one or more fields. Which SQL function helps with this?

COALESCE is the tool for replacing nulls with a non-null value in calculations. It returns the first non-null value from its arguments, so COALESCE(product, product_code) gives you product when it’s present, and falls back to product_code when product is null. This keeps calculations from being affected by nulls by providing a real value to use. COALESCE is also standard SQL and portable across databases, and it can take more than two inputs if needed. In contrast, NULLIF would turn values into NULL when they’re equal, which doesn’t help replace nulls, and ISNULL/IFNULL are dialect-specific and may behave differently in different systems.

COALESCE is the tool for replacing nulls with a non-null value in calculations. It returns the first non-null value from its arguments, so COALESCE(product, product_code) gives you product when it’s present, and falls back to product_code when product is null. This keeps calculations from being affected by nulls by providing a real value to use.

COALESCE is also standard SQL and portable across databases, and it can take more than two inputs if needed. In contrast, NULLIF would turn values into NULL when they’re equal, which doesn’t help replace nulls, and ISNULL/IFNULL are dialect-specific and may behave differently in different systems.

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