为什么将sql查询转换为Zend_Db样式？

Question

I would like to ask why people use zend_db style?

eg

     $select = $d2b->select()
             ->from('users', array('userid','username'))
             ->where('userid=?', 2);

 $result = $d2b->fetchRow($select);
 echo $result->username;

instead of

$result = $d2b->fetchAll('SELECT * FROM users WHERE userid = ?', 2);
echo $result[0]->username;

Which one is better? Or is it the same, just for maintainability.

Answer 1

One reason is that using Zend_db style abstracts out the generation of SQL; this means that we switching between database engines can be as easy as swapping out a class, rather than having to re-write incompatible queries.

Furthermore, Zend_db abstracts out SQL query escaping, greatly reducing the risk of SQL injection attacks. It also provides database querying functionality for those who do not know SQL.

Answer 2

The end result is the same, so it's down to your personal preferences on readabiliy and maintainability.

The one advantage of the fluent interface style is that it makes it easier to build the queries up programatically, eg:

$select = $d2b->select()
         ->from('users', array('userid','username'));

if ([some condition]) {
    $select->where('userid = ?', 2);
} else {
    $select->where('userid = ?', 62);
}