void $DB_DataObject->joinAdd (
object $dataobject
,
string $joinType
,
string $joinAs
,
string $joinCol
)
Builds a Join Query, by adding another dataobject to this one. Be careful when using this, raw queries may be clearer than using joinAdd.
Thanks to Stijn de Reede for the implementation of this.
object $obj - joining object (no value resets the join)
string $joinType - "LEFT" | "INNER " | "RIGHT" | ""
INNER is default, "" indicates just select ... from a,b,c with no join and links are added as where items.
Note: 'LEFT' is the same as LEFT OUTER.
string $joinAs - if you want to select the table as anther name
useful when you want to select multiple columns from a secondary table.
string $joinCol - The column on This objects table to match,needed
if this table links to the child object in
multiple places eg.
using specific join Columns
user->friend (is a id of a person) user->mother (is a id of another person)
This function can not be called statically.
The Examples below are not tested, use DB_DataObject::debugLevel(1), to see what exactly is going on when you use this, and send the author some better examples..
Simple simple Join
<?php
// (requires links.ini to be set up correctly)
// get all the images for product 24
$i = new DataObject_Image();
$pi = new DataObjects_Product_image();
$pi->product_id = 24; // set the product id to 24
$i->joinAdd($pi); // add the product_image connectoin
$i->find();
while ($i->fetch()) {
// do stuff
}
?>
Resulting SQL
More Complex Join query
<?php
// an example with 2 joins
// get all the images linked with products or productgroups
$i = new DataObject_Image();
$pi = new DataObject_Product_image();
$pgi = new DataObject_Productgroup_image();
$i->joinAdd($pi);
$i->joinAdd($pgi);
$i->find();
while ($i->fetch()) {
// do stuff
}
?>
Resulting SQL