MySQL Bugs: #53037: Delete Foreign Key Columns deletes columns participating in other relationships

Bug #53037	Delete Foreign Key Columns deletes columns participating in other relationships
Submitted:	21 Apr 2010 19:56	Modified:	20 Aug 2010 11:49
Reporter:	Mark Drolshagen	Email Updates:
Status:	Closed	Impact on me:	None
Category:	MySQL Workbench: Modeling	Severity:	S3 (Non-critical)
Version:	5.2.19	OS:	Any
Assigned to:	Alfredo Kojima	CPU Architecture:	Any
Tags:	foreign keys, relationships

Description:
In EER Diagramming, when deleting a relationship, the user is asked to confirm whether to delete the child columns in use by the relationship.

If the user presses 'Yes', my expectation is that the child columns would be deleted only if they are *not* actively participating in another relationship. Instead, EER deletes all columns in the child table that participate in the relationship being deleted, even if they are actively participating in other relationships. This can cause other relationships to break and generate a loss of data should a critical column be dropped during synchronization.

How to repeat:
- Within an EER Diagram, right-click on an existing relationship, select 'Delete'.

- The user is presented with a popup named 'Delete Foreign Key Columns' that asks Please confirm whether columns used by the foreign key should be deleted too". 

- Press 'Yes'.

- All child columns are deleted.

Suggested fix:
Delete only child fields that have exactly one existing relationship (the one being deleted).

Schema to demonstrate the problem

Attachment: bug53037.mwb (application/octet-stream, text), 6.66 KiB.

Thank you for the problem report.

An internal check has been added so that columns referenced by FKs from other tables are left untouched.

Thank you for your bug report. This issue has already been fixed in the latest released version of that product, which you can download at

  http://www.mysql.com/downloads/