MySQL Error 1451 - mysql

Question

Command:
DELETE FROM `meetings`.`meetingparticipants` WHERE `meetingparticipants`.`idParticipants` =503 AND `meetingparticipants`.`idMeetings` =83
I know I have a simple error in my database. I am attempting to delete a row from the meeting participants table and receiving the following error:
#1451 - Cannot delete or update a parent row: a foreign key constraint fails (`meetings`.`invoices`, CONSTRAINT `fk_meetingid` FOREIGN KEY (`fk_meetingid`) REFERENCES `meetingparticipants` (`idMeetings`) ON DELETE NO ACTION ON UPDATE NO ACTION)
Any ideas? I think I need a foreign key relationship between the participant table and the meeting-participant table with updates, but I rather confirm or see if there are any suggestions??
CREATE TABLE IF NOT EXISTS `invoices` (
`idinvoices` int(11) NOT NULL AUTO_INCREMENT,
`fk_invoiceType` int(11) DEFAULT NULL,
`DocNum` varchar(10) DEFAULT NULL,
`DZ` varchar(9) DEFAULT NULL,
`Amount` decimal(10,2) DEFAULT NULL,
`fk_meetingid` int(11) DEFAULT NULL,
`fk_participantid` int(11) DEFAULT NULL,
`invoiceNotes` varchar(255) DEFAULT NULL,
`invoiceDocuments` blob,
PRIMARY KEY (`idinvoices`),
UNIQUE KEY `DOC_Num` (`DocNum`),
KEY `fk_invoiceType` (`fk_invoiceType`),
KEY `fk_meetingid` (`fk_meetingid`),
KEY `fk_participantid` (`fk_participantid`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=1014 ;
-- --------------------------------------------------------
--
-- Table structure for table `invoicestatus`
--
CREATE TABLE IF NOT EXISTS `invoicestatus` (
`idinvoiceStatus` int(11) NOT NULL AUTO_INCREMENT,
`invoiceStatus` varchar(45) NOT NULL,
PRIMARY KEY (`idinvoiceStatus`),
UNIQUE KEY `invoiceStatus_UNIQUE` (`invoiceStatus`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=23 ;
-- --------------------------------------------------------
--
-- Table structure for table `invoicestatushistory`
--
CREATE TABLE IF NOT EXISTS `invoicestatushistory` (
`fk_invoiceStatus` int(11) DEFAULT NULL,
`statusStamp` datetime DEFAULT NULL,
`fk_idinvoices` int(11) NOT NULL,
`idinvoiceStatusHistory` int(11) NOT NULL AUTO_INCREMENT,
PRIMARY KEY (`idinvoiceStatusHistory`,`fk_idinvoices`),
KEY `invoiceStatusHistory` (`fk_invoiceStatus`),
KEY `invoiceid` (`fk_idinvoices`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=1015 ;
-- --------------------------------------------------------
--
-- Table structure for table `invoicetypes`
--
CREATE TABLE IF NOT EXISTS `invoicetypes` (
`idinvoiceTypes` int(11) NOT NULL AUTO_INCREMENT,
`invoiceType` varchar(45) DEFAULT NULL,
PRIMARY KEY (`idinvoiceTypes`),
UNIQUE KEY `invoiceType_UNIQUE` (`invoiceType`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=21 ;
-- --------------------------------------------------------
--
-- Table structure for table `meetingparticipants`
--
CREATE TABLE IF NOT EXISTS `meetingparticipants` (
`idParticipants` int(11) NOT NULL,
`idMeetings` int(11) NOT NULL,
`invited` tinyint(1) DEFAULT NULL,
`attended` tinyint(1) DEFAULT NULL,
`travelCostsReimbursed` tinyint(1) DEFAULT NULL,
`ParticipantFeeEligible` tinyint(1) DEFAULT NULL,
`ParticipantFeeProcessed` tinyint(1) DEFAULT NULL,
PRIMARY KEY (`idParticipants`,`idMeetings`),
KEY `idParticipants` (`idParticipants`),
KEY `idMeetings` (`idMeetings`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
-- --------------------------------------------------------
--
-- Table structure for table `meetings`
--
CREATE TABLE IF NOT EXISTS `meetings` (
`idmeetings` int(11) NOT NULL AUTO_INCREMENT,
`meetingName` varchar(45) NOT NULL,
`beginDate` date DEFAULT NULL,
`endDate` date DEFAULT NULL,
`location` varchar(45) DEFAULT NULL,
`meetingNotes` varchar(255) DEFAULT NULL,
`meetingDocuments` blob,
`fk_programID` int(110) DEFAULT NULL,
PRIMARY KEY (`idmeetings`),
UNIQUE KEY `meetingName_UNIQUE` (`meetingName`),
KEY `programid` (`fk_programID`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=85 ;
-- --------------------------------------------------------
--
-- Table structure for table `participants`
--
CREATE TABLE IF NOT EXISTS `participants` (
`idparticipants` int(11) NOT NULL AUTO_INCREMENT,
`firstName` varchar(45) DEFAULT NULL,
`lastName` varchar(45) NOT NULL,
`preferredName` varchar(75) DEFAULT NULL,
`email` varchar(45) DEFAULT NULL,
`affiliation` varchar(45) DEFAULT NULL,
`foreignNational` tinyint(1) DEFAULT NULL,
`grantPaid` tinyint(1) DEFAULT NULL,
`bannerid` varchar(9) DEFAULT NULL,
`participantNotes` varchar(255) DEFAULT NULL,
`participantDocuments` blob,
`visaType` int(11) DEFAULT NULL,
PRIMARY KEY (`idparticipants`),
UNIQUE KEY `bannerid_UNIQUE` (`bannerid`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=507 ;
-- --------------------------------------------------------
--
-- Table structure for table `programs`
--
CREATE TABLE IF NOT EXISTS `programs` (
`idprograms` int(11) NOT NULL AUTO_INCREMENT,
`ProgramName` varchar(45) NOT NULL,
PRIMARY KEY (`idprograms`),
UNIQUE KEY `ProgramName_UNIQUE` (`ProgramName`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=21 ;
-- --------------------------------------------------------
--
-- Table structure for table `users`
--
CREATE TABLE IF NOT EXISTS `users` (
`userID` int(11) NOT NULL AUTO_INCREMENT,
`userName` varchar(25) NOT NULL,
`userPassword` varchar(10) NOT NULL DEFAULT 'password',
`userLevel` int(11) NOT NULL,
PRIMARY KEY (`userID`),
UNIQUE KEY `userName` (`userName`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=5 ;
-- --------------------------------------------------------
--
-- Table structure for table `visatypes`
--
CREATE TABLE IF NOT EXISTS `visatypes` (
`idvisaTypes` int(11) NOT NULL AUTO_INCREMENT,
`visaType` varchar(45) DEFAULT NULL,
`paymentInstructions` varchar(500) DEFAULT NULL,
PRIMARY KEY (`idvisaTypes`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=27 ;
--
-- Constraints for dumped tables
--
--
-- Constraints for table `invoices`
--
ALTER TABLE `invoices`
ADD CONSTRAINT `fk_invoiceType` FOREIGN KEY (`fk_invoiceType`) REFERENCES `invoicetypes` (`idinvoiceTypes`) ON DELETE NO ACTION ON UPDATE NO ACTION,
ADD CONSTRAINT `fk_meetingid` FOREIGN KEY (`fk_meetingid`) REFERENCES `meetingparticipants` (`idMeetings`) ON DELETE NO ACTION ON UPDATE NO ACTION,
ADD CONSTRAINT `fk_participantid` FOREIGN KEY (`fk_participantid`) REFERENCES `meetingparticipants` (`idParticipants`) ON DELETE NO ACTION ON UPDATE NO ACTION;
--
-- Constraints for table `invoicestatushistory`
--
ALTER TABLE `invoicestatushistory`
ADD CONSTRAINT `invoiceid` FOREIGN KEY (`fk_idinvoices`) REFERENCES `invoices` (`idinvoices`) ON DELETE NO ACTION ON UPDATE CASCADE,
ADD CONSTRAINT `invoiceStatusHistory` FOREIGN KEY (`fk_invoiceStatus`) REFERENCES `invoicestatus` (`idinvoiceStatus`) ON DELETE NO ACTION ON UPDATE CASCADE;
--
-- Constraints for table `meetings`
--
ALTER TABLE `meetings`
ADD CONSTRAINT `programid` FOREIGN KEY (`fk_programID`) REFERENCES `programs` (`idprograms`) ON DELETE NO ACTION ON UPDATE NO ACTION;

Answer 1

You have a foreign key constraint on the invoices table that is named "fk_meetingid", but references the meetingparticipants table, which is an association table. It would seem to me that if an invoice were linked to a meeting that it should be linked directly to the meetings table.

Answer 2

From the manual:
http://dev.mysql.com/doc/refman/5.5/en/innodb-foreign-key-constraints.html
NO ACTION: A keyword from standard SQL. In MySQL, equivalent to
RESTRICT. InnoDB rejects the delete or update operation for the parent
table if there is a related foreign key value in the referenced table.
Some database systems have deferred checks, and NO ACTION is a
deferred check. In MySQL, foreign key constraints are checked
immediately, so NO ACTION is the same as RESTRICT.
If I understand your schema, (which is unlikely after looking at it for 30 seconds), you probably want to use ON DELETE CASCADE so that a participants invoices are deleted when you delete the participant. If you need to keep the invoices but delete the participant then choose ON DELETE SET NULL