为什么Zend Framework在where子句中添加括号？

Question

I have the following query:

$tagCordQuery = $this->freqDb->select()
                    ->from("rr_amplifiers", "*")
                    ->join("amplifiers_coordinate", "amplifiers_coordinate.name = TRIM(TRAILING '0' FROM  rr_amplifiers.name)", array())
                    ->where("amplifiers_coordinate.name IN(?)", $apsName);

Where $apsName it's an array.

The problem is when this array has only one element the query had extra parenthesis like this:

SELECT `rr_amplifiers`.* FROM `rr_amplifiers`
 INNER JOIN `amplifiers_coordinate` ON amplifiers_coordinate.name = TRIM(TRAILING '0' FROM  rr_amplifiers.name) WHERE (amplifiers_coordinate.name IN('xpto'))

Why this it's happen?

Answer 1

It's in case you did something like this:

->where("amplifiers_coordinate.name IN(?) OR something = 1", $apsName);

(ie include an OR condition in the WHERE). Without the parentheses, the query wouldn't work as you'd expect.

Answer 2

Zend Framework allows you to add more than one where statement. Always wrapping the clause in parentheses prevents unintended logic from occuring.