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MySQL IFNULL()

The IFNULL() function returns a specified value if the expression is NULL. If the expression is not NULL, it returns the expression itself. It is useful for handling NULL values in data.

Examples

1. Using IFNULL with a Column

SELECT king_name, IFNULL(reign_period, 'Unknown') AS period_description FROM tamil_kings_auto_increment;

Code Explanation: This query returns 'Unknown' if reign_period is NULL, otherwise it returns the actual reign_period.

2. Using IFNULL with a Calculation

SELECT king_name, IFNULL(reign_years, 0) AS years_of_reign FROM tamil_kings_auto_increment;

Code Explanation: This query returns 0 if reign_years is NULL, otherwise it returns the actual value.

Best Practices

  • Use IFNULL() to handle NULL values gracefully and avoid issues in calculations or displays.
  • Specify a meaningful default value when handling NULLs.

Key Takeaways

  • The IFNULL() function replaces NULL values with a specified default value.
  • It is useful for ensuring data consistency and readability.
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