MySQL Bugs: #74199: Create constraint key type UNIQUENULL to prohibit multiple null values

Bug #74199	Create constraint key type UNIQUENULL to prohibit multiple null values
Submitted:	3 Oct 2014 0:42
Reporter:	Marco Janc	Email Updates:
Status:	Open	Impact on me:	None
Category:	MySQL Server	Severity:	S4 (Feature request)
Version:	5.6	OS:	Any
Assigned to:		CPU Architecture:	Any
Tags:	column, constraint, null, unique

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Description:
By ANSI standards multiple null columns are permitted on UNIQUE constrained columns.

What about a new key type UNIQUENULL to prohibit multiple null values.

Not having such an option needs really annoying workarounds such as a non nullable helper column which sets replacement data for null values in trigger.

How to repeat:
Feature request, nothing to repeat.

Suggested fix:
Create UNIQUENULL key constraint