->joinAdd()
Synopsis
void $DB_DataObject->joinAdd (
object $dataobject
,
string $joinType
,
string $joinAs
,
string $joinCol
)
Description
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.
Parameter
-
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)
Note
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..
Example
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
SELECT * FROM image
LEFT JOIN product_image
ON (image.id = product_image.image_id)
WHERE product_image.id = 24
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
SELECT * FROM image
LEFT JOIN product_image
ON (image.id = product_image.image_id)
LEFT JOIN productgroup
ON (image.id = productgroup_image.image_id);