What potential issue might arise when using the "AND" keyword instead of a comma in a SQL query in PHP?

Using the "AND" keyword instead of a comma in a SQL query in PHP can lead to syntax errors or unexpected results. To solve this issue, ensure that each condition in the WHERE clause is separated by a comma and use the "AND" keyword to combine multiple conditions within each clause.

$query = "SELECT * FROM table_name WHERE column1 = 'value1' AND column2 = 'value2'";