what does %s means here?

Question

What does %s mean?

$sql = "SELECT * 
          FROM page_table 
         WHERE page_name = '%s' 
         LIMIT 1";

Answer 1

It is a formatted string where %s is a placeholder. I suspect that $sql is handed to sprintf to transform it into a real query. Example:

$name = 'posts';
$sql = "SELECT * FROM page_table WHERE page_name = '%s' LIMIT 1";
$formattedSql = sprintf($sql, $name);

This will generate a query looking like:

SELECT * FROM page_table WHERE page_name = 'posts' LIMIT 1

This is very useful when you don't want to fiddle around with quotes and doublequotes.