问题
I have a mysql DB with 3 tables:
- Campaigns
id
code
name
- Columns
id
name
- Values
id
idColumn
value
The relationship beetween Campaigns and Columns is many to many:
- ColumnsCampaign
id
idColumn
idCampaign
and the relationship beetween Columns and Values is one to many.
I have this query that returns all values for each campaign:
return Campaigns::addSelect('id','code','name')
->whereHas('typeCampaign', function ($q) use ($idTypeCampaign,$idMenu)
{
$q->where('typeCampaign.id',$idTypeCampaign)
->whereHas('menus', function ($q) use ($idMenu){
$q->where('menus.id',$idMenu);
});
})//this part define which campaign i want with a certain menu
->with('columns.values')//with this i include the campaign columns and its values
->get();
My problem is that if i have different values for the same column i dont know to which campaign is associated. How can i solve this issue? Is it correct to create a relationship table between campaigns and values?
回答1:
It seems that the structure of the designed tables is not matching to its underlying domain.
If mutliple values can be assigned to a given column id (idColumn), then either an extra key field (which is actually a campaignId) is required to be introduced in table Values or create an extra table that associates campaig id, columns id and values id. The third option -this is what I recommned actually - is to unify the table Columns and Values.
回答2:
This isn't (yet?) an answer but it might be a little more obvious to the rest of us if the structure was more like this:
Campaigns
campaign_id *
code
name
Columns
column_id *
name
campaigns_columns
Campaign_id *
Column_id *
* = (component of) PRIMARY KEY
来源：https://stackoverflow.com/questions/30371161/relationship-between-3-tables