Decomposition.java

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 * Copyright: GPL v3                                                          *
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 * This program is free software: you can redistribute it and/or modify       *
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package dbaCore.logic.normalization;

import dbaCore.data.Attribute;
import dbaCore.data.ForeignKeyConstraint;
import dbaCore.data.RelationSchema;
import dbaCore.logic.Analysis.GeneralRelationCheck;
import dbaCore.logic.Analysis.RelationUtils;

import java.util.ArrayList;

public abstract class Decomposition implements NormalizationAlgorithm {
  protected GeneralRelationCheck checker = new GeneralRelationCheck();

  public RelationSchema getMinimalRelation(RelationSchema relationToNormalize) {
    RelationSchema relation = relationToNormalize.getClone();

    relation.setFunctionalDependencies(checker.getMinimalSetOfFds(relation.getFunctionalDependencies()));

    RelationUtils.getInstance().uniteFdsWithSameLeftSide(relation.getFunctionalDependencies());

    relation.restoreReferences();

    return relation;
  }

  /**
   * Updates the primary- and foreignKeys of the given relations
   *
   * @param oldRelation the old relation
   * @param newRelation the newly created relation
   * @param foreignKeys a ArrayList as Container for new foreignKeys
   */
  public void updatePrimaryAndForeignKeys(RelationSchema oldRelation, RelationSchema newRelation,
                                          ArrayList<ForeignKeyConstraint> foreignKeys) {

    // set primaryKey for newly created relation
    RelationUtils.getInstance().resetPrimaryKey(newRelation);

    // update foreignkeyConstraints
    for (Attribute newAttr : newRelation.getAttributes()) {
      for (Attribute oldAttr : oldRelation.getAttributes()) {
        if (newAttr.getIsPrimaryKey()) {
          if (newAttr.getName().equals(oldAttr.getName())) {
            foreignKeys.add(new ForeignKeyConstraint(oldRelation.getName(), oldAttr.getName(), newRelation.getName(),
              newAttr.getName()));
            oldAttr.setIsForeignKey(true);
          }
        }
      }
    }

  }
}