How to use ifnull in oracle

Oracle IFNULL function is used to return a default value when the specified column or expression is NULL. Its usage includes: replacing NULL values ​​to prevent errors. Missing data were imputed for data analysis. Convert NULL values ​​to specific values ​​to improve readability.

Usage of IFNULL function in Oracle

The IFNULL function is an Oracle built-in function that is used to specify column or A default value is returned when the expression is NULL. It is essential for handling NULL values ​​and ensuring data integrity.

Syntax

<code>IFNULL(expression, default_value)</code>

• expression: The column or expression to check.
• default_value: The default value to be returned if expression is NULL.

Usage

The IFNULL function can be used in the following scenarios:

• Replace NULL values ​​to prevent errors.
• Fill in missing data for data analysis.
• Convert NULL values ​​to specific values ​​to improve readability.

Example

The following example replaces NULL values ​​with 0:

<code>SELECT IFNULL(salary, 0) FROM employees;</code>

The following example fills NULL values ​​with "Unknown":

<code>SELECT IFNULL(name, 'Unknown') FROM customers;</code>

The following example converts a NULL value to the string "N/A":

<code>SELECT IFNULL(address, 'N/A') FROM contacts;</code>

Note

• default_value can be any valid Oracle value, including string, number, or date.
• If expression is not NULL, the IFNULL function returns the value of expression.
• IFNULL function can be nested to handle multiple levels of NULL values.

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