Help with unique constraint

[jayrulez]

I have the following tables

CREATE TABLE IF NOT EXISTS `cms_channel` (
  `id` int(10) NOT NULL AUTO_INCREMENT,
  `userId` int(10) NOT NULL,
  `name` varchar(100) NOT NULL,
  PRIMARY KEY (`id`),
  KEY `FK_channel_user` (`userId`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;



CREATE TABLE IF NOT EXISTS `cms_channel_category` (
  `id` int(10) NOT NULL AUTO_INCREMENT,
  `parentId` int(10) DEFAULT NULL,
  `name` varchar(100) NOT NULL,
  `description` varchar(200) DEFAULT NULL,
  PRIMARY KEY (`id`),
  UNIQUE KEY `name` (`parentId`,`name`),
  KEY `FK_channel_category_channel_category` (`parentId`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;



CREATE TABLE IF NOT EXISTS `cms_channel_category_assignment` (
  `categoryId` int(10) NOT NULL,
  `channelId` int(10) NOT NULL,
  PRIMARY KEY (`categoryId`,`channelId`),
  KEY `FK_channel_category_assignment_channel` (`channelId`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

with the following relational constraints

ALTER TABLE `cms_channel_category_assignment`
  ADD CONSTRAINT `FK_channel_category_assignment_category` FOREIGN KEY (`categoryId`) REFERENCES `cms_channel_category` (`id`) ON DELETE CASCADE ON UPDATE CASCADE,
  ADD CONSTRAINT `FK_channel_category_assignment_channel` FOREIGN KEY (`channelId`) REFERENCES `cms_channel` (`id`) ON DELETE CASCADE ON UPDATE CASCADE;

As you can see, the relationship between channel_category and channel is of a many to many type.

I want to add a constraint that says a user (channel.userId) can have only 1 channel of the same name (channel.name) in the category (channel_category_assignment.categoryId) to be joined on channel.id=channel_category_assignment.channelId...

Is there a way to set this constraint from mysql or do i need to take care of that through the server side code?