What is the difference between using HAVING and WHERE clauses in PHP MySQL queries for filtering results?

The main difference between using HAVING and WHERE clauses in PHP MySQL queries for filtering results is that the WHERE clause is used to filter rows before any grouping is done, while the HAVING clause is used to filter rows after the grouping has been done. This means that the WHERE clause is applied before the data is grouped, while the HAVING clause is applied after the data is grouped. 

// Using WHERE clause to filter results
$query = "SELECT * FROM table_name WHERE column_name = 'value'";
$result = mysqli_query($connection, $query);

// Using HAVING clause to filter results
$query = "SELECT column_name, COUNT(*) FROM table_name GROUP BY column_name HAVING COUNT(*) > 1";
$result = mysqli_query($connection, $query);

Keywords

PHP MySQL HAVING clause WHERE clause filtering

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