Question

I have a number of objects. They can be sorted into groups. When a user “drags” an object into a group, I INSERT a record into my db

INSERT INTO t1
  (group_id, item_id, project_id, user_id) 
VALUES 
  ($groupID, $itemID, $projectID, $userID)

There can be multiple objects in the same group and those objects can be moved from one group to another. When I move the objects into another group, I don’t need to create another record, but rather only update group_id.

---

EDIT:

I think I need to do something like this afterall:

table structure
t1.id
t1.group_id
t1.item_id
t1.project_id
t1.user_id

if ("SELECT id, group_id FROM t1 
   WHERE item_id = $itemID
   AND project_id = $projectID
   AND user_id = $userID")) {

   // if found 
   UPDATE t1 
   SET group_id = $groupID
   WHERE id = $ID

} else {

   INSERT INTO t1
   (group_id, item_id, project_id, user_id) 
   VALUES ($groupID, $itemID, $projectID, $userID)

Answer 1

It sounds like u should place a if statement when moving from a group to another group to update only the object being move. Say for instance if I am selecting an object from its initial(beginning) space I would add the insert statement. If I am moving an object that has already been grouped to another group I would add an update statement. Finally if I am taking an item out of all groups completely I would issue a delete statement that will remove the object from the table.

pseudo code

if object = new
{
INSERT INTO t1 (group_id, item_id, project_id, user_id) 
VALUES ($groupID, $itemID, $projectID, $userID)
}
if object = group
}
UPDATE t1 
SET group_id = $newgroupID
WHERE item_id = $itemID;
}
if object = banned
}
delete from t1 where item_id = $itemID
}

This sequence of code should be placed on each container that you are dragging your objects to so that it can check for the proper requirements.