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MySQL NULL Values

A NULL value in MySQL represents missing or undefined data. NULL is different from zero or an empty string.

Examples with Tamil Kings

1. Checking for NULL Values

SELECT * FROM tamil_kings_auto_increment
WHERE reign_period IS NULL;

Code Explanation: This query retrieves records where the reign_period column has a NULL value.

2. Checking for NOT NULL Values

SELECT * FROM tamil_kings_auto_increment
WHERE king_name IS NOT NULL;

Code Explanation: This query retrieves records where the king_name column does not have a NULL value.

Best Practices

  • Use IS NULL and IS NOT NULL to check for NULL values in conditions.
  • Avoid using = NULL or != NULL because these comparisons will not work as expected.

Key Takeaways

  • NULL represents missing or undefined data.
  • Use IS NULL and IS NOT NULL to check for NULL values.
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