ATK Relations: Difference between revisions

Revision as of 10:10, 28 December 2006

A relation defines a relation between two tables. One or more records in the first table belong to one or more records in the second table. A one to many relation would be '1 library has N books'. Below is a list of the relations that are currently available in ATK.

atkOneToOneRelation - 'A person has one address'
atkOneToManyRelation - 'A department has many employees'
atkManyToOneRelation - 'A project has a projectleader (that can lead multiple projects)'
atkManyToManyRelation - 'A shopper buys multiple products, a product can be bought by multiple shoppers'

atkManyBoolRelation

Document me!

atkManyToOneTreeRelation

The atkManyToOneTree relation will build a dropdown that looks like:

Record A
  Record B
  Record C
     Record D
     Record E
Record F

It could be used together with atkTreeNode with AF_PARENT.

atkMatrixRelation

The atkMatrixRelation is no longer maintained and probably does not work. Over the years that ATK has existed, there haven't been many uses for the atkMatrixRelation.

atkSecureRelation

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atkShuttleRelation

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@@ Line 4: / Line 4: @@
 * [[atkOneToManyRelation]] - 'A department has many employees'
 * [[atkManyToOneRelation]] - 'A project has a projectleader (that can lead multiple projects)'
+* [[atkManyToManyRelation]] - 'A shopper buys multiple products, a product can be bought by multiple shoppers'
-== atkManyToManyRelation ==
-This relation can be created with an intermediate table to store the relations.
-A Many-To-Many-Relation basically consist of a atkOneToMany relation to the intermediate table. The intermediate node has two atkManyToOne relations defined.
-'''Example'''
-One person (node A) can have several skills (node B) and the same skill applies to more than one person.
-[[image:atkManyToMany.jpg|center]]
-If, in the example above, a skill is removed, this skill must be removed for all employees. This can be achieved by adding the AF_CASCADE_DELETE flag to the atkOneToManyRelation in node B:
- atkOneToMany(“unique dummy”,
-              “mymod.A_B”,
-              “b_id”,
-              AF_HIDE|AF_CASCADE_DELETE);
-Normally you assign skills to a person (an not the other way round), so the atkOneToManyRelation in this node must be hidden.
-And on the other hand, if an employee is deleted, the correspoding record(s) in the intermediate table must be removed as well.
- atkOneToMany(“unique dummy”,
-              “mymod.A_B”,
-              “a_id”,
-              AF_CASCADE_DELETE);
-'''Be careful''' when using the AF_HIDE flag in the itermediate (A_B) node for the atkManyToOneRelation, in combination with multilanguage fields. When a relation is hidden, the key (a_id) will not be processed and no check on the language is done. This causes the added record to appear multiple times (once for every language), since a_id is not unique in the intermediate table.
 ==atkManyBoolRelation==