Re: [MS_AccessPros] Relationship Definition

 

Sarah-

Allow Zero Length may let the user store a "blank" instead of a Null when no value is entered.  That was the problem.  RI ignores Null values, but a "blank" won't match anything in the other table, so you get an error.

John Viescas, Author

Effective SQL

SQL Queries for Mere Mortals 

Microsoft Access 2010 Inside Out

Microsoft Access 2007 Inside Out

Microsoft Access 2003 Inside Out

Building Microsoft Access Applications 

http://www.viescas.com/ 

(Paris, France)

On Jul 12, 2016, at 9:37 PM, sarahk@schemesoftware.com [MS_Access_Professionals] <MS_Access_Professionals@yahoogroups.com> wrote:

Thanks John,

I changed the zero length property and ran the query and now I can enforce the integrity.

I dont understand the zero length property:if the field is not filled in , then what is stored in the table if allow zero length is yes? If allow zero length is no?.

Sarah

---In MS_Access_Professionals@yahoogroups.com, <JohnV@...> wrote :

Sarah-

Make sure the Allow Zero Length property of the field is set to NO.  That alone may fix the problem.  Or you might need to run a query:

UPDATE Products

SET [Product Class] = Null

WHERE Len([Product Class]) = 0;

John Viescas, Author

Effective SQL

SQL Queries for Mere Mortals 

Microsoft Access 2010 Inside Out

Microsoft Access 2007 Inside Out

Microsoft Access 2003 Inside Out

Building Microsoft Access Applications 

http://www.viescas.com/ 

(Paris, France)

On Jul 12, 2016, at 9:07 PM, sarahk@... [MS_Access_Professionals] <MS_Access_Professionals@yahoogroups.com> wrote:

The data type of the Product Class is text. How to I check if it is a true Null value?. How do I set it to Null if it's not filled in on the data entry form?.

Sarah
---In MS_Access_Professionals@yahoogroups.com, <JohnV@...> wrote :

Sarah-

What is the data type of Product Class?  As long as the field in the Product table contains a true Null value, you should be able to define the rule.  I suspect you have some non-Null or other invalid values.

John Viescas, Author

Effective SQL

SQL Queries for Mere Mortals 

Microsoft Access 2010 Inside Out

Microsoft Access 2007 Inside Out

Microsoft Access 2003 Inside Out

Building Microsoft Access Applications 

http://www.viescas.com/ 

(Paris, France)

On Jul 12, 2016, at 7:46 PM, sarahk@... [MS_Access_Professionals] <MS_Access_Professionals@yahoogroups.com> wrote:

I have 2 tables:

Product Class

Product

The Product table has a field Product Class that relates to the Product Class table. This field in the Product table is optional.

 I am trying to define a Relationship with 'referential integrity' between the Product Class and the Product table, but because I have records in the Product table that dont have the Class filled in, I am getting a message 'Product violates referential integrity'. Is there any way around this?. I have tried all Join Types but I am getting the same message on all of them. 

Thanks for your answers.

Sarah

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Posted by: John Viescas <johnv@msn.com>

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