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Re: grandparent - parent - child link entity [message #2643 is a reply to message #2641]

Fri, 31 December 2010 10:22

gpatti
Messages: 287
Registered: August 2008

Senior Member

Hi Tony,

I'm afraid I don't have an easy way to draw the schema so I hope the following rambling description will suffice. Please let me know if this creates additional questions.

The application will be to allow a person to create a dance routine for a given dance type from a set number of figures.

Table dance_type
- dance_type_id (PK)
- other columns

Table figure
- figure_id (PK)
- other columns

Table dance_figure (link table allowing many-many between dance_type and figure)
- dance_type_id
- figure_id

Now a new link table is introduced and relationships used to join dance_figure to itself in a many-many relationship

Table follow
- dance_type_id
- figure_id
- follow_id

Two relationships between dance_figure and follow usng figure_id and follow_id as foreign key
1 - dance_type_id and figure id as snr
2 - dance_type_id and follow_id as jnr

The concept is that a dance_type consists of a number of figures. A figure may exist in more than one dance_type (hence many-many link relationship using dance_figure).

Any figure (within a particular dance_type) can have one or more allowed following figures.

Therefore, I need to be able to able to specify for each row in dance_figure, which other figures are valid follows (it isn't allowed to mix dance_types, so dance_id as follow does not need to be included in the follow table).

In terms of the framework, I wanted to be able to navigate from the dance_type list screen to a link screen allowing the valid dance_figures to be selected (this part is easy and is complete). However, for a selected dance_figure I then want to navigate to another link screen to select the valid follows.

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[Message index]

		grandparent - parent - child link entity By: gpatti on Thu, 30 December 2010 11:15
		Re: grandparent - parent - child link entity By: AJM on Fri, 31 December 2010 04:46
		Re: grandparent - parent - child link entity By: gpatti on Fri, 31 December 2010 10:22
		Re: grandparent - parent - child link entity By: AJM on Fri, 31 December 2010 12:15
		Re: grandparent - parent - child link entity By: gpatti on Fri, 31 December 2010 13:06

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