Question

I’m migrating a database from MySQL 5 to SQL Server 2008. I’m using the SQL Server Migration Assistant, and it’s giving me an error that I don’t understand.

I have tables that look like this:

Table A
  ID (primary key)
  ProductionBatch
  Manufacturer
  LotNo
  Cost
  (and a bunch of other fields)

Table B
  ProductionBatch (primary key)
  Manufacturer (primary key)
  LotNo (primary key)
  Cost (primary key)
  (and a bunch of other fields)

In MySQL, the four fields I’ve indicated in both tables form the primary key in Table B and a foreign key in Table A; I don’t want any new records inserted into table B unless there’s a match on those fields in Table A. Works fine in MySQL, but the Migration Assistant is giving me the following error:

M2SS0048: Foreign Key does not contains all the columns of Primary/Unique Key

The grammar error aside, I can’t figure out what this error means. Is it that I’m allowing null values for those fields in Table A? Or that they do not have to be unique in Table A? I tried using an autoincrementing integer as a primary key for Table B (instead of the compound key), but that didn’t seem to help.

Any ideas or suggestions would be appreciated.

EDIT: To be clear, my foreign key is on Table B. I put records into Table A first, then put records into Table B. But I don’t want to put records into Table B that don’t match any in Table A.

SECOND EDIT: I’ve been asked to show the code for this problem. As I told the questioner, I’ve been using a simple example to ask the question; my tables are actually more complicated, and I thought a simplified version would be easier to answer. But here are the actual tables, if anyone would like to see what I’m really doing. The actual fields I’m linking on are QCBatchID, LaboratoryName, Constituent, and Fraction (I used generic ones in the above example).

Table A is:

CREATE TABLE `chemistry_qc` (
`QCBatchID` varchar(12) COLLATE utf8_unicode_ci NOT NULL,
`LaboratoryName` varchar(45) COLLATE utf8_unicode_ci NOT NULL,
`Constituent` varchar(45) COLLATE utf8_unicode_ci NOT NULL,
`Fraction` enum('Not Reported','NA','Total','Dissolved','TR') COLLATE utf8_unicode_ci    
NOT NULL,
`LabSampleType` varchar(12) COLLATE utf8_unicode_ci DEFAULT NULL,
`PercentRecovery` decimal(5,2) DEFAULT NULL,
`RPD` double(5,2) DEFAULT NULL,
PRIMARY KEY (`QCBatchID`,`LaboratoryName`,`Constituent`,`Fraction`),
CONSTRAINT `fk_chem_qc_chem` FOREIGN KEY (`QCBatchID`, `LaboratoryName`,   `Constituent`, `Fraction`) REFERENCES `chemistry` (`LaboratoryName`, `QCBatchID`, `Constituent`, `Fraction`) ON DELETE NO ACTION ON UPDATE NO ACTION
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci

Table B is:

CREATE TABLE `chemistry` (
`ChemistryID` int(11) NOT NULL AUTO_INCREMENT,
`StationID` varchar(45) COLLATE utf8_unicode_ci NOT NULL,
`EventStartDateTime` datetime NOT NULL,
`SampleStartDateTime` datetime DEFAULT NULL,
`SampleEndDateTime` datetime DEFAULT NULL,
`SampleType` varchar(45) COLLATE utf8_unicode_ci DEFAULT NULL,
`FieldSampleID` varchar(45) COLLATE utf8_unicode_ci DEFAULT NULL,
`Matrix` varchar(12) COLLATE utf8_unicode_ci DEFAULT NULL,
`FieldQC` varchar(20) COLLATE utf8_unicode_ci DEFAULT NULL,
`GrabComposite` enum('C','G') COLLATE utf8_unicode_ci DEFAULT NULL,
`EventRepresentation` varchar(20) COLLATE utf8_unicode_ci DEFAULT NULL,
`CollectionMethod` varchar(12) COLLATE utf8_unicode_ci DEFAULT NULL,
`LaboratoryName` varchar(45) COLLATE utf8_unicode_ci DEFAULT NULL,
`LabSampleID` varchar(45) COLLATE utf8_unicode_ci DEFAULT NULL,
`ConstituentType` varchar(20) COLLATE utf8_unicode_ci DEFAULT NULL,
`Constituent` varchar(45) COLLATE utf8_unicode_ci DEFAULT NULL,
`CASNumber` varchar(20) COLLATE utf8_unicode_ci DEFAULT NULL,
`Fraction` enum('TR','Dissolved','Total','Not Reported','NA') COLLATE utf8_unicode_ci   DEFAULT NULL,
`QCBatchID` varchar(12) COLLATE utf8_unicode_ci DEFAULT NULL,
`SamplePrepMethod` varchar(45) COLLATE utf8_unicode_ci DEFAULT NULL,
`AnalysisType` varchar(5) COLLATE utf8_unicode_ci DEFAULT NULL,
`LabSampleType` varchar(4) COLLATE utf8_unicode_ci DEFAULT NULL,
`AnalyteType` varchar(5) COLLATE utf8_unicode_ci DEFAULT NULL,
`SamplePrepDate` date DEFAULT NULL,
`ReportedValue` double DEFAULT NULL,
`Units` varchar(12) COLLATE utf8_unicode_ci DEFAULT NULL,
`NumericQualifier` enum('>=','<=','>','<','=') COLLATE utf8_unicode_ci DEFAULT NULL,
`DataQualifier` text COLLATE utf8_unicode_ci,
`ReportingLimit` double DEFAULT NULL,
`MethodDetectionLimit` double DEFAULT NULL,
`PercentMoisture` decimal(3,2) DEFAULT NULL,
`MethodReference` varchar(12) COLLATE utf8_unicode_ci DEFAULT NULL,
`MethodNumber` varchar(20) COLLATE utf8_unicode_ci DEFAULT NULL,
`AnalysisDateTime` datetime DEFAULT NULL,
`Dilution` int(3) DEFAULT NULL,
`SampleNotes` longtext COLLATE utf8_unicode_ci,
PRIMARY KEY (`ChemistryID`),
KEY `fk_chemistry_event1` (`StationID`,`EventStartDateTime`),
KEY `fk_chemistry_laboratory1` (`LaboratoryName`),
KEY `ChemistryID` (`ChemistryID`,`StationID`,`EventStartDateTime`),
KEY `fk_chemistry_c_EventRepresentation1` (`EventRepresentation`),
KEY `fk_chemistry_c_collectionmethod1` (`CollectionMethod`),
KEY `fk_chemistry_c_sampletype1` (`SampleType`),
KEY `fk_chemistry_c_matrix` (`Matrix`),
KEY `fk_chemistry_c_methods`      (`Constituent`,`ConstituentType`,`Units`,`MethodReference`,`MethodNumber`),
KEY `fk_chemistry_sampleprepmethod1` (`SamplePrepMethod`),
KEY `fk_chemistry_analysistype` (`AnalysisType`),
KEY `fk_chemistry_analytetype` (`AnalyteType`),
KEY `fk_chemistry_labsampletype` (`LabSampleType`),
KEY `ChemistryID_2` (`ChemistryID`,`StationID`),
KEY `LaboratoryName` (`LaboratoryName`,`Constituent`,`Fraction`,`QCBatchID`),
KEY `QCBatchID_4` (`QCBatchID`,`LaboratoryName`,`Constituent`,`Fraction`),
KEY `LaboratoryName_4` (`LaboratoryName`,`QCBatchID`,`Constituent`,`Fraction`),
CONSTRAINT `chemistry_analysistype` FOREIGN KEY (`AnalysisType`) REFERENCES   `c_analysistype` (`AnalysisType`) ON DELETE NO ACTION ON UPDATE NO ACTION,
CONSTRAINT `chemistry_ibfk_10` FOREIGN KEY (`SamplePrepMethod`) REFERENCES `c_sampleprepmethod` (`SamplePrepMethod`) ON DELETE NO ACTION ON UPDATE NO ACTION,
CONSTRAINT `chemistry_ibfk_11` FOREIGN KEY (`Constituent`, `ConstituentType`, `Units`, `MethodReference`, `MethodNumber`) REFERENCES `c_methods` (`Constituent`, `ConstituentType`, `Units`, `MethodReference`, `MethodNumber`) ON DELETE NO ACTION ON   UPDATE NO ACTION,
CONSTRAINT `chemistry_ibfk_2` FOREIGN KEY (`AnalyteType`) REFERENCES `c_analytetype` (`AnalyteType`) ON DELETE NO ACTION ON UPDATE NO ACTION,
CONSTRAINT `chemistry_ibfk_3` FOREIGN KEY (`CollectionMethod`) REFERENCES `c_collectionmethod` (`CollectionMethod`) ON DELETE NO ACTION ON UPDATE NO ACTION,
CONSTRAINT `chemistry_ibfk_4` FOREIGN KEY (`EventRepresentation`) REFERENCES `c_eventrepresentation` (`EventRepresentation`) ON DELETE NO ACTION ON UPDATE NO ACTION,
CONSTRAINT `chemistry_ibfk_5` FOREIGN KEY (`Matrix`) REFERENCES `c_matrix` (`Matrix`) ON DELETE NO ACTION ON UPDATE NO ACTION,
CONSTRAINT `chemistry_ibfk_6` FOREIGN KEY (`SampleType`) REFERENCES `c_sampletype` (`SampleType`) ON DELETE NO ACTION ON UPDATE NO ACTION,
CONSTRAINT `chemistry_ibfk_7` FOREIGN KEY (`StationID`, `EventStartDateTime`)   REFERENCES `event` (`StationID`, `EventStartDateTime`) ON DELETE NO ACTION ON UPDATE NO ACTION,
CONSTRAINT `chemistry_ibfk_8` FOREIGN KEY (`LaboratoryName`) REFERENCES `laboratory` (`LaboratoryName`) ON DELETE NO ACTION ON UPDATE NO ACTION,
CONSTRAINT `chemistry_ibfk_9` FOREIGN KEY (`LabSampleType`) REFERENCES `c_labsampletype` (`LabSampleType`) ON DELETE NO ACTION ON UPDATE NO ACTION) ENGINE=InnoDB AUTO_INCREMENT=206971 DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci  

Answer 1

I’ll keep only the relevant columns from the 2 tables:

Table A:

CREATE TABLE chemistry_qc (
  QCBatchID       varchar(12) COLLATE utf8_unicode_ci  NOT NULL,
  LaboratoryName  varchar(45) COLLATE utf8_unicode_ci  NOT NULL,
  Constituent     varchar(45) COLLATE utf8_unicode_ci  NOT NULL,
  Fraction        enum('Not Reported','NA','Total','Dissolved','TR') 
                              COLLATE utf8_unicode_ci  NOT NULL,
  --- more columns

  PRIMARY KEY (QCBatchID, LaboratoryName, Constituent, Fraction),

  CONSTRAINT fk_chem_qc_chem 
    FOREIGN KEY (QCBatchID, LaboratoryName, Constituent, Fraction) 
      REFERENCES chemistry 
                (LaboratoryName, QCBatchID, Constituent, Fraction) 
    ON DELETE NO ACTION 
    ON UPDATE NO ACTION

) ENGINE=InnoDB 
  DEFAULT CHARSET=utf8 
  COLLATE=utf8_unicode_ci ;

Table B:

CREATE TABLE chemistry (
  ChemistryID     int(11) NOT NULL AUTO_INCREMENT,
  --- more columns
  LaboratoryName  varchar(45) COLLATE utf8_unicode_ci  DEFAULT NULL,
  --- more columns
  Constituent     varchar(45) COLLATE utf8_unicode_ci  DEFAULT NULL,
  Fraction        enum('TR','Dissolved','Total','Not Reported','NA') 
                             COLLATE utf8_unicode_ci  DEFAULT NULL,
  QCBatchID       varchar(12) COLLATE utf8_unicode_ci  DEFAULT NULL,
  --- more columns

PRIMARY KEY (ChemistryID),

KEY fk_chemistry_laboratory1 (LaboratoryName),
--- more KEYs
KEY LaboratoryName (LaboratoryName, Constituent, Fraction, QCBatchID),
KEY QCBatchID_4 (QCBatchID, LaboratoryName, Constituent, Fraction),
      --- this key should have been needed for your FK reference

KEY LaboratoryName_4 (LaboratoryName , QCBatchID, Constituent, Fraction),
      --- this key was needed for your FK reference

--- CONSTRAINTS 

) ENGINE=InnoDB 
  AUTO_INCREMENT=206971 
  DEFAULT CHARSET=utf8 
  COLLATE=utf8_unicode_ci ; 

---

For the record, this a FOREIGN KEY from table A (chemistry_qc) to table B (chemistry)

---

There are two errors in your FOREIGN KEY constraint. The first was done by you (and assisted by MySQL). You have the two referencing and the referenced compound key with different ordering:

CONSTRAINT fk_chem_qc_chem 
    FOREIGN KEY (QCBatchID, LaboratoryName, Constituent, Fraction) 
      REFERENCES chemistry 
                (LaboratoryName, QCBatchID, Constituent, Fraction) 
             ---    |||             |||   
             --- *** wrong order here *** ---

It should be:

CONSTRAINT fk_chem_qc_chem 
    FOREIGN KEY (QCBatchID, LaboratoryName, Constituent, Fraction) 
      REFERENCES chemistry 
                (QCBatchID, LaboratoryName, Constituent, Fraction) 

MySQL should have complained when you tried to add an FK where a VARCHAR(45) was referencing a VARCHAR(12) but it didn’t.

---

The second error is that your FK is referencing a key that is neither PRIMARY nor UNIQUE. Another assistance by MySQL to screw things by allowing an FK to a non-unique column-compound.

So, you should have either (case-1) declared that key as UNIQUE in table chemistry or (case-2) your FK should be the other way around, from table B to A (which already has a PRIMARY KEY on this compound).

Which of the two is correct, depends on the relationships of your data:

Does every chemistry have 0 or 1 chemistry_qc? That’s case-1 (and you have a 1:1 relationship or to be more exact a 0..1 :: 1).

Does every chemistry_qc have 0 or more chemistry? That’s case-2 (and you have a common 1:n relationship, a 1 :: 0..n in the above notation).

---

Finally, it should be clear that what caused the migration error was that the wizard you used, was (correctly) expecting a FOREIGN KEY constraint to reference a PRIMARY or a UNIQUE compound.