Re: Can't Delete From Mapping Table (when no column is named ID)

[Igor Polevoy]

ActiveJDBC depends on ID columns for deletes, updates and relationships. If you do not have IDs, then you will need to write custom SQL.
I suggest to add ID, because it is cheap anyway.



On 01/23/2015 01:16 AM, Gianna Giavelli wrote:

I'm trying to delete the mapping table entry between 2 tables. 

Say I have Boys and Dogs

so I have a mapping table

MTBL_BOYS_DOGS

   BOYID INT,

   DOGID INT

So I try to delete from it but I cant after looking up the object and calling Delete, because there is no ID column

I don't want an id column because to me, these are both foreign keys

So how do I do this?

MtblBoyDog oMtblBoyDog = MtblBoyDog.findFirst("BOYID=? and DOGID=?", strBoyId, strDogID);

        if (oMtblBoyDog != null)

        oMtblBoyDog.delete();

org.javalite.activejdbc.DBException: com.mysql.jdbc.exceptions.MySQLSyntaxErrorException: Unknown column 'id' in 'where clause', Query: DELETE FROM mtbl_boy_dog WHERE id= ?, params: null

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[Gianna Giavelli]

My mistake was using MTBL (mapping tables) as a direct object from the standpoint of ActiveJDBC.

Instead, I used the add and remove, which works WITHOUT ID column in the mapping table. I do for both add and remove. Here is code for remove: works fine without ID. Took me a bit to realize you don't treat a mapping table as direct model class its "hidden". If you DO need to do so, then yes ad an ID column. 

        Category oCategory = Category.findById(strCatId);

    User     oUser     = User.findById(strUserId);

    if (oCategory == null || oUser == null)

    System.out.println ("nulls!");

    else

    oCategory.remove(oUser);