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Re: Do entities require a primary key?
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Re: Do entities require a primary key?


  • Subject: Re: Do entities require a primary key?
  • From: Chuck Hill <email@hidden>
  • Date: Wed, 9 Dec 2009 15:35:36 -0800


On Dec 9, 2009, at 3:25 PM, Johnny Miller wrote:

The table has two columns an "IP_FROM" and an "IP_TO", each contains an IP number.

According to the manual after you convert an IP address to an IP number it can only resolve to one row in the database i.e.

IP_FROM <= X <= IP_TO

So, I'd assume that the multi-column PK would work because the combo of IP_FROM and IP_TO has to be unique. I've never created column pk like that before - can I find the info in the Apple supplied docs?

Nothing to it, just mark both as primary key columns in Entity Modeler. Look at a many to many join table for an example.



Chuck



re: raw SQL. Yeah, I planned on that.

Thanks a lot,

Johnny


On Dec 9, 2009, at 1:12 PM, Chuck Hill wrote:

Are the rows unique? If so, you can make a multi-column PK. EOF needs _something_ to uniquely identify them if you want to make EOs out of the data. You might also want to consider just raw SQL (raw rows) and / or making a cache of these and avoiding the EO overhead.

Chuck

On Dec 9, 2009, at 3:04 PM, Johnny Miller wrote:

Hi,

I just purchased a database that does IP address to country resolution. I'm reverse engineering the database into a Wonder Framework and I realized that the single table in the database doesn't have a primary key. WOLips doesn't like this and throws an error stating the entity does not have a primary key.

Should I just create a primary key field and leave it blank? Or is there a better alternative? This is going to be a read only database.

Thanks in advance,

Johnny Miller
Kahalawai Media Corp
http://www.kahalawai.com



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-- Chuck Hill Senior Consultant / VP Development

Practical WebObjects - for developers who want to increase their overall knowledge of WebObjects or who are trying to solve specific problems.
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Johnny Miller Kahalawai Media Corp http://www.kahalawai.com




-- Chuck Hill Senior Consultant / VP Development

Practical WebObjects - for developers who want to increase their overall knowledge of WebObjects or who are trying to solve specific problems.
http://www.global-village.net/products/practical_webobjects








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  • Follow-Ups:
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References: 
 >Do entities require a primary key? (From: Johnny Miller <email@hidden>)
 >Re: Do entities require a primary key? (From: Chuck Hill <email@hidden>)
 >Re: Do entities require a primary key? (From: Johnny Miller <email@hidden>)

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