/**
* Executes the normalization procedures defined in "procedures" on the given schema, exits when
* the targetNf is reached
*
* @param schema the relation to normalize
* @return the results of the Normalization
*/
private NormalizationResult startNormalizing(
RelationSchema schema, ArrayList<NormalizationAlgorithm> procedures, NormalForm targetNf) {
NormalizationResult result = new NormalizationResult();
NormalizationResult tempResult;
result.getRelations().add(schema);
for (NormalizationAlgorithm procedure : procedures) {
// Quit if NF already reached
if (checker.getNF(result.getRelations()).ordinal() >= targetNf.ordinal()) {
break;
}
tempResult = (NormalizationResult) result.getClone();
for (RelationSchema relation : tempResult.getRelations()) {
procedure.normalize(relation, result, false);
}
}
compactFds(result);
return result;
}
public NormalizationResult normalize(
RelationSchema relationToNormalize, NormalForm actualNF, NormalForm targetNF) {
RelationSchema relation = relationToNormalize.getClone();
RelationSchema backupRelation;
NormalizationResult result;
// Pick up lonely Attributes (in no Functional dependency)
RelationUtils.getInstance().determineAllAttributes(relation);
// Set primary-key if not present
if (RelationUtils.getInstance().getPrimaryKey(relation).getAttributes().isEmpty()) {
Key newPrimaryKey = RelationUtils.getInstance().getKey(relation);
for (Attribute attribute : relation.getAttributes()) {
if (newPrimaryKey.getAttributes().contains(attribute)) {
attribute.setIsPrimaryKey(true);
}
}
}
backupRelation = relation.getClone();
normalizationProcedures.clear();
switch (actualNF) {
case FIRST:
switch (targetNF) {
case SECOND:
// 1.NF ==> 2.NF
normalizationProcedures.add(new DecompositionTo2NF());
break;
case THIRD:
// 1.NF ==> 3.NF
normalizationProcedures.add(new SyntheseTo3NF());
break;
case BOYCECODD:
// 1.NF ==> BCNF
normalizationProcedures.add(new SyntheseTo3NF());
normalizationProcedures.add(new DecompositionToBCNF());
break;
default:
throw new IllegalArgumentException();
}
break;
case SECOND:
switch (targetNF) {
case THIRD:
// 2.NF ==> 3.NF
normalizationProcedures.add(new SyntheseTo3NF());
break;
case BOYCECODD:
// 2.NF ==> BCNF
normalizationProcedures.add(new SyntheseTo3NF());
normalizationProcedures.add(new DecompositionToBCNF());
break;
default:
throw new IllegalArgumentException();
}
break;
case THIRD:
// 3.NF ==> BCNF
normalizationProcedures.add(new DecompositionToBCNF());
break;
default:
throw new IllegalArgumentException();
}
result = startNormalizing(relation, normalizationProcedures, targetNF);
if (result.getRelations().isEmpty()) {
result.getRelations().add(backupRelation);
}
return result;
}
/**
* Compacts all Fd's of the given Relations
*
* @param result the NormalizationResult to work with
*/
private void compactFds(NormalizationResult result) {
for (RelationSchema relation : result.getRelations()) {
uniteFdsWithSameLeftSide(relation);
}
}