Zend_Db_Select : multiple from clause - zend-framework

Question

Hy,
I have some problem vith Zend_Db_Select.
I have 2 variable : category and city. These 2 variables may have a value or they may be unset.
So I verify:
$status = '`p`.status = 1';
if($catID){
$catSQL = "`p`.parent = {$catID}";
}else{
$catSQL = '1=1';
}
if($city){
$citySQL = "`pm`.`meta_key` = 'oras' and `pm`.`meta_value` = {$city}";
$citySelect = array('pm' => 'postsmeta');
$condCity = "`p`.`ID` = `pm`.`parent_id`";
}else{
$citySQL = '1=1';
$citySelect = NULL;
$condCity = '1=1';
}
Now here is my query:
$select = $db->select()
->from( array('p' => 'posts'))
->from($citySelect)
->where($status)
->where($catSQL)
->where($condCity)
->where($citySQL)
;
The problem is that if city is empty I have something like
$select = $db->select()
->from( array('p' => 'posts'))
->from('')
->where(1=1)
->where(1=1)
->where(1=1)
->where(1=1)
;
The questions is how can I remove from('') from my query if city is empty.
Thank you!

Answer 1

Simply,
$select = $db->select()
->from( array('p' => 'posts'));
if($someConditionIsTrue) {
$select->join($table, $condition);
}
$select->where('field_value = ?', 'value1');
if($someConditionIsTrue) {
$select->where('another_field = ?', 'value 2');
}
Hope it helps.
Please use this syntax $select->where('another_field = ?', 'value 2'); for proper escaping values to prevent SQL injections.