Bug #7409 InnoDB: function to count usage of a key as foreign key in the child tables

• Submitted: 18 Dec 2004 18:05
• Modified: 13 May 2010 16:04
• Reporter: Zrin Ziborski
• Status: Open
• Category: MySQL Server: InnoDB storage engine
• Severity: S4 (Feature request)
• Assigned to: Assigned Account
• CPU Architecture: Any

[18 Dec 2004 18:05] Zrin Ziborski

Description:
It would be helpful to have functions like IS_USED() and/or USE_COUNT() that would tell if a value of (primary) key is used in any child table and how often it is used, respectively.

e.g.
in child table(s):
	FOREIGN KEY (some_field) REFERENCES film(flm_id)
for parent table `film`
	SELECT USE_COUNT(flm_id) FROM film;
for each row it would return the count of child rows referencing it.

How to repeat:
not applicable (feature request)

Suggested fix:
the functionality is already implemented, it seems that it is just needed to expose this functions in the API (i.e. as SQL extension).