package org.apache.torque.engine.database.model;
   
   /*
    * Copyright 2001-2004 The Apache Software Foundation.
    * 
    * Licensed under the Apache License, Version 2.0 (the "License");
    * you may not use this file except in compliance with the License.
    * You may obtain a copy of the License at
    * 
   *      http://www.apache.org/licenses/LICENSE-2.0
   * 
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  import java.util.ArrayList;
  import java.util.Hashtable;
  import java.util.Iterator;
  import java.util.List;
  
  import org.apache.commons.lang.StringUtils;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  
  import org.apache.torque.engine.EngineException;
  
  import org.xml.sax.Attributes;
  
  /***
   * Data about a table used in an application.
   *
   * @author <a href="mailto:leon@opticode.co.za">Leon Messerschmidt</a>
   * @author <a href="mailto:jvanzyl@apache.org">Jason van Zyl</a>
   * @author <a href="mailto:mpoeschl@marmot.at>Martin Poeschl</a>
   * @author <a href="mailto:jmcnally@collab.net>John McNally</a>
   * @author <a href="mailto:dlr@collab.net>Daniel Rall</a>
   * @author <a href="mailto:byron_foster@byron_foster@yahoo.com>Byron Foster</a>
   * @version $Id: Table.java,v 1.8 2004/08/23 00:30:10 seade Exp $
   */
  public class Table implements IDMethod
  {
      /*** Logging class from commons.logging */
      private static Log log = LogFactory.getLog(Table.class);
  
      //private AttributeListImpl attributes;
      private List columnList;
      private List foreignKeys;
      private List indices;
      private List unices;
      private List idMethodParameters;
      private String name;
      private String description;
      private String javaName;
      private String idMethod;
      private String javaNamingMethod;
      private Database tableParent;
      private List referrers;
      private List foreignTableNames;
      private boolean containsForeignPK;
      private Column inheritanceColumn;
      private boolean skipSql;
      private boolean abstractValue;
      private String alias;
      private String enterface;
      private String pkg;
      private String baseClass;
      private String basePeer;
      private Hashtable columnsByName;
      private Hashtable columnsByJavaName;
      private boolean needsTransactionInPostgres;
      private boolean heavyIndexing;
      private boolean forReferenceOnly;
  
  
      /***
       * Default Constructor
       */
      public Table()
      {
          this(null);
      }
  
      /***
       * Constructs a table object with a name
       *
       * @param name table name
       */
      public Table(String name)
      {
          this.name = name;
          columnList = new ArrayList();
          foreignKeys = new ArrayList(5);
          indices = new ArrayList(5);
          unices = new ArrayList(5);
          columnsByName = new Hashtable();
         columnsByJavaName = new Hashtable();
     }
 
     /***
      * Load the table object from an xml tag.
      *
      * @param attrib xml attributes
      * @param defaultIdMethod defined at db level
      */
     public void loadFromXML(Attributes attrib, String defaultIdMethod)
     {
         name = attrib.getValue("name");
         javaName = attrib.getValue("javaName");
         idMethod = attrib.getValue("idMethod");
 
         // retrieves the method for converting from specified name to
         // a java name.
         javaNamingMethod = attrib.getValue("javaNamingMethod");
         if (javaNamingMethod == null)
         {
             javaNamingMethod = getDatabase().getDefaultJavaNamingMethod();
         }
 
         if ("null".equals(idMethod))
         {
             idMethod = defaultIdMethod;
         }
         skipSql = "true".equals(attrib.getValue("skipSql"));
         // pkg = attrib.getValue("package");
         abstractValue = "true".equals(attrib.getValue("abstract"));
         baseClass = attrib.getValue("baseClass");
         basePeer = attrib.getValue("basePeer");
         alias = attrib.getValue("alias");
         heavyIndexing = "true".equals(attrib.getValue("heavyIndexing"))
                 || (!"false".equals(attrib.getValue("heavyIndexing"))
                 && getDatabase().isHeavyIndexing());
         description = attrib.getValue("description");
         enterface = attrib.getValue("interface");
     }
 
     /***
      * <p>A hook for the SAX XML parser to call when this table has
      * been fully loaded from the XML, and all nested elements have
      * been processed.</p>
      *
      * <p>Performs heavy indexing and naming of elements which weren't
      * provided with a name.</p>
      */
     public void doFinalInitialization()
     {
         // Heavy indexing must wait until after all columns composing
         // a table's primary key have been parsed.
         if (heavyIndexing)
         {
             doHeavyIndexing();
         }
 
         // Name any indices which are missing a name using the
         // appropriate algorithm.
         doNaming();
     }
 
     /***
      * <p>Adds extra indices for multi-part primary key columns.</p>
      *
      * <p>For databases like MySQL, values in a where clause must
      * match key part order from the left to right.  So, in the key
      * definition <code>PRIMARY KEY (FOO_ID, BAR_ID)</code>,
      * <code>FOO_ID</code> <i>must</i> be the first element used in
      * the <code>where</code> clause of the SQL query used against
      * this table for the primary key index to be used.  This feature
      * could cause problems under MySQL with heavily indexed tables,
      * as MySQL currently only supports 16 indices per table (i.e. it
      * might cause too many indices to be created).</p>
      *
      * <p>See <a href="http://www.mysql.com/doc/E/X/EXPLAIN.html">the
      * manual</a> for a better description of why heavy indexing is
      * useful for quickly searchable database tables.</p>
      */
     private void doHeavyIndexing()
     {
         if (log.isDebugEnabled())
         {
             log.debug("doHeavyIndex() called on table " + name);
         }
 
         List pk = getPrimaryKey();
         int size = pk.size();
 
         try
         {
             // We start at an offset of 1 because the entire column
             // list is generally implicitly indexed by the fact that
             // it's a primary key.
             for (int i = 1; i < size; i++)
             {
                 addIndex(new Index(this, pk.subList(i, size)));
             }
         }
         catch (EngineException e)
         {
             log.error(e, e);
         }
     }
 
     /***
      * Names composing objects which haven't yet been named.  This
      * currently consists of foreign-key and index entities.
      */
     private void doNaming()
     {
         int i;
         int size;
         String name;
 
         // Assure names are unique across all databases.
         try
         {
             for (i = 0, size = foreignKeys.size(); i < size; i++)
             {
                 ForeignKey fk = (ForeignKey) foreignKeys.get(i);
                 name = fk.getName();
                 if (StringUtils.isEmpty(name))
                 {
                     name = acquireConstraintName("FK", i + 1);
                     fk.setName(name);
                 }
             }
 
             for (i = 0, size = indices.size(); i < size; i++)
             {
                 Index index = (Index) indices.get(i);
                 name = index.getName();
                 if (StringUtils.isEmpty(name))
                 {
                     name = acquireConstraintName("I", i + 1);
                     index.setName(name);
                 }
             }
 
             for (i = 0, size = unices.size(); i < size; i++)
             {
                 Unique unique = (Unique) unices.get(i);
                 name = unique.getName();
                 if (StringUtils.isEmpty(name))
                 {
                     name = acquireConstraintName("U", i + 1);
                     unique.setName(name);
                 }
             }
         }
         catch (EngineException nameAlreadyInUse)
         {
             log.error(nameAlreadyInUse, nameAlreadyInUse);
         }
     }
 
     /***
      * Macro to a constraint name.
      *
      * @param nameType constraint type
      * @param nbr unique number for this constraint type
      * @return unique name for constraint
      * @throws EngineException
      */
     private final String acquireConstraintName(String nameType, int nbr)
             throws EngineException
     {
         List inputs = new ArrayList(4);
         inputs.add(getDatabase());
         inputs.add(getName());
         inputs.add(nameType);
         inputs.add(new Integer(nbr));
         return NameFactory.generateName(NameFactory.CONSTRAINT_GENERATOR,
                                         inputs);
     }
 
     /***
      * Gets the value of base class for classes produced from this table.
      *
      * @return The base class for classes produced from this table.
      */
     public String getBaseClass()
     {
         if (isAlias() && baseClass == null)
         {
             return alias;
         }
         else if (baseClass == null)
         {
             return getDatabase().getBaseClass();
         }
         else
         {
             return baseClass;
         }
     }
 
     /***
      * Set the value of baseClass.
      * @param v  Value to assign to baseClass.
      */
     public void setBaseClass(String v)
     {
         this.baseClass = v;
     }
 
     /***
      * Get the value of basePeer.
      * @return value of basePeer.
      */
     public String getBasePeer()
     {
         if (isAlias() && basePeer == null)
         {
             return alias + "Peer";
         }
         else if (basePeer == null)
         {
             return getDatabase().getBasePeer();
         }
         else
         {
             return basePeer;
         }
     }
 
     /***
      * Set the value of basePeer.
      * @param v  Value to assign to basePeer.
      */
     public void setBasePeer(String v)
     {
         this.basePeer = v;
     }
 
     /***
      * A utility function to create a new column from attrib and add it to this
      * table.
      *
      * @param attrib xml attributes for the column to add
      * @return the added column
      */
     public Column addColumn(Attributes attrib)
     {
         Column col = new Column();
         col.setTable(this);
         col.loadFromXML(attrib);
         addColumn(col);
         return col;
     }
 
     /***
      * Adds a new column to the column list and set the
      * parent table of the column to the current table
      *
      * @param col the column to add
      */
     public void addColumn(Column col)
     {
         col.setTable (this);
         if (col.isInheritance())
         {
             inheritanceColumn = col;
         }
         columnList.add(col);
         columnsByName.put(col.getName(), col);
         columnsByJavaName.put(col.getJavaName(), col);
         col.setPosition(columnList.size());
         needsTransactionInPostgres |= col.requiresTransactionInPostgres();
     }
 
     /***
      * A utility function to create a new foreign key
      * from attrib and add it to this table.
      *
      * @param attrib the xml attributes
      * @return the created ForeignKey
      */
     public ForeignKey addForeignKey(Attributes attrib)
     {
         ForeignKey fk = new ForeignKey();
         fk.loadFromXML(attrib);
         addForeignKey(fk);
         return fk;
     }
 
     /***
      * Gets the column that subclasses of the class representing this
      * table can be produced from.
      */
     public Column getChildrenColumn()
     {
         return inheritanceColumn;
     }
 
     /***
      * Get the objects that can be created from this table.
      */
     public List getChildrenNames()
     {
         if (inheritanceColumn == null
                 || !inheritanceColumn.isEnumeratedClasses())
         {
             return null;
         }
         List children = inheritanceColumn.getChildren();
         List names = new ArrayList(children.size());
         for (int i = 0; i < children.size(); i++)
         {
             names.add(((Inheritance) children.get(i)).getClassName());
         }
         return names;
     }
 
     /***
      * Adds the foreign key from another table that refers to this table.
      *
      * @param fk A foreign key refering to this table
      */
     public void addReferrer(ForeignKey fk)
     {
         if (referrers == null)
         {
             referrers = new ArrayList(5);
         }
         referrers.add(fk);
     }
 
     /***
      * Get list of references to this table.
      *
      * @return A list of references to this table
      */
     public List getReferrers()
     {
         return referrers;
     }
 
     /***
      * Set whether this table contains a foreign PK
      *
      * @param b
      */
     public void setContainsForeignPK(boolean b)
     {
         containsForeignPK = b;
     }
 
     /***
      * Determine if this table contains a foreign PK
      */
     public boolean getContainsForeignPK()
     {
         return containsForeignPK;
     }
 
     /***
      * A list of tables referenced by foreign keys in this table
      *
      * @return A list of tables
      */
     public List getForeignTableNames()
     {
         if (foreignTableNames == null)
         {
             foreignTableNames = new ArrayList(1);
         }
         return foreignTableNames;
     }
 
     /***
      * Adds a new FK to the FK list and set the
      * parent table of the column to the current table
      *
      * @param fk A foreign key
      */
     public void addForeignKey(ForeignKey fk)
     {
         fk.setTable (this);
         foreignKeys.add(fk);
 
         if (foreignTableNames == null)
         {
             foreignTableNames = new ArrayList(5);
         }
         if (!foreignTableNames.contains(fk.getForeignTableName()))
         {
             foreignTableNames.add(fk.getForeignTableName());
         }
     }
 
     /***
      * Return true if the column requires a transaction in Postgres
      */
     public boolean requiresTransactionInPostgres()
     {
         return needsTransactionInPostgres;
     }
 
     /***
      * A utility function to create a new id method parameter
      * from attrib and add it to this table.
      */
     public IdMethodParameter addIdMethodParameter(Attributes attrib)
     {
         IdMethodParameter imp = new IdMethodParameter();
         imp.loadFromXML(attrib);
         addIdMethodParameter(imp);
         return imp;
     }
 
 
     /***
      * Adds a new ID method parameter to the list and sets the parent
      * table of the column associated with the supplied parameter to this table.
      *
      * @param imp The column to add as an ID method parameter.
      */
     public void addIdMethodParameter(IdMethodParameter imp)
     {
         imp.setTable(this);
         if (idMethodParameters == null)
         {
             idMethodParameters = new ArrayList(2);
         }
         idMethodParameters.add(imp);
     }
 
     /***
      * Adds a new index to the index list and set the
      * parent table of the column to the current table
      */
     public void addIndex(Index index)
     {
         index.setTable (this);
         indices.add(index);
     }
 
     /***
      * A utility function to create a new index
      * from attrib and add it to this table.
      */
     public Index addIndex(Attributes attrib)
     {
         Index index = new Index();
         index.loadFromXML(attrib);
         addIndex(index);
         return index;
     }
 
     /***
      * Adds a new Unique to the Unique list and set the
      * parent table of the column to the current table
      */
     public void addUnique(Unique unique)
     {
         unique.setTable(this);
         unices.add(unique);
     }
 
     /***
      * A utility function to create a new Unique
      * from attrib and add it to this table.
      *
      * @param attrib the xml attributes
      */
     public Unique addUnique(Attributes attrib)
     {
         Unique unique = new Unique();
         unique.loadFromXML(attrib);
         addUnique(unique);
         return unique;
     }
 
     /***
      * Get the name of the Table
      */
     public String getName()
     {
         return name;
     }
 
     /***
      * Set the name of the Table
      */
     public void setName(String newName)
     {
         name = newName;
     }
 
     /***
      * Get the description for the Table
      */
     public String getDescription()
     {
         return description;
     }
 
     /***
      * Set the description for the Table
      *
      * @param newDescription description for the Table
      */
     public void setDescription(String newDescription)
     {
         description = newDescription;
     }
 
     /***
      * Get name to use in Java sources
      */
     public String getJavaName()
     {
         if (javaName == null)
         {
             List inputs = new ArrayList(2);
             inputs.add(name);
             inputs.add(javaNamingMethod);
             try
             {
                 javaName = NameFactory.generateName(NameFactory.JAVA_GENERATOR,
                                                     inputs);
             }
             catch (EngineException e)
             {
                 log.error(e, e);
             }
         }
         return javaName;
     }
 
     /***
      * Set name to use in Java sources
      */
     public void setJavaName(String javaName)
     {
         this.javaName = javaName;
     }
 
     /***
      * Get the method for generating pk's
      */
     public String getIdMethod()
     {
         if (idMethod == null)
         {
             return IDMethod.NO_ID_METHOD;
         }
         else
         {
             return idMethod;
         }
     }
 
     /***
      * Set the method for generating pk's
      */
     public void setIdMethod(String idMethod)
     {
         this.idMethod = idMethod;
     }
 
     /***
      * Skip generating sql for this table (in the event it should
      * not be created from scratch).
      * @return value of skipSql.
      */
     public boolean isSkipSql()
     {
         return (skipSql || isAlias() || isForReferenceOnly());
     }
 
     /***
      * Set whether this table should have its creation sql generated.
      * @param v  Value to assign to skipSql.
      */
     public void setSkipSql(boolean  v)
     {
         this.skipSql = v;
     }
 
     /***
      * JavaName of om object this entry references.
      * @return value of external.
      */
     public String getAlias()
     {
         return alias;
     }
 
     /***
      * Is this table specified in the schema or is there just
      * a foreign key reference to it.
      * @return value of external.
      */
     public boolean isAlias()
     {
         return (alias != null);
     }
 
     /***
      * Set whether this table specified in the schema or is there just
      * a foreign key reference to it.
      * @param v  Value to assign to alias.
      */
     public void setAlias(String v)
     {
         this.alias = v;
     }
 
 
     /***
      * Interface which objects for this table will implement
      * @return value of interface.
      */
     public String getInterface()
     {
         return enterface;
     }
 
     /***
      * Interface which objects for this table will implement
      * @param v  Value to assign to interface.
      */
     public void setInterface(String  v)
     {
         this.enterface = v;
     }
 
     /***
      * When a table is abstract, it marks the business object class that is
      * generated as being abstract. If you have a table called "FOO", then the
      * Foo BO will be <code>public abstract class Foo</code>
      * This helps support class hierarchies
      *
      * @return value of abstractValue.
      */
     public boolean isAbstract()
     {
         return abstractValue;
     }
 
     /***
      * When a table is abstract, it marks the business object
      * class that is generated as being abstract. If you have a
      * table called "FOO", then the Foo BO will be
      * <code>public abstract class Foo</code>
      * This helps support class hierarchies
      *
      * @param v  Value to assign to abstractValue.
      */
     public void setAbstract(boolean  v)
     {
         this.abstractValue = v;
     }
 
     /***
      * Get the value of package.
      *
      * @return value of package.
      */
     public String getPackage()
     {
         if (pkg != null)
         {
             return pkg;
         }
         else
         {
             return this.getDatabase().getPackage();
         }
     }
 
     /***
      * Set the value of package.
      *
      * @param v  Value to assign to package.
      */
     public void setPackage(String v)
     {
         this.pkg = v;
     }
 
     /***
      * Returns a List containing all the columns in the table
      * 
      * @return a List containing all the columns
      */
     public List getColumns()
     {
         return columnList;
     }
 
     /***
      * Utility method to get the number of columns in this table
      */
     public int getNumColumns()
     {
         return columnList.size();
     }
 
     /***
      * Returns a List containing all the FKs in the table
      * 
      * @return a List containing all the FKs
      */
     public List getForeignKeys()
     {
         return foreignKeys;
     }
 
     /***
      * Returns a Collection of parameters relevant for the chosen
      * id generation method.
      */
     public List getIdMethodParameters()
     {
         return idMethodParameters;
     }
 
     /***
      * A name to use for creating a sequence if one is not specified.
      *
      * @return name of the sequence
      */
     public String getSequenceName()
     {
         String result = null;
         if (getIdMethod().equals(NATIVE))
         {
             List idMethodParams = getIdMethodParameters();
             if (idMethodParams == null)
             {
                 result = getName() + "_SEQ";
             }
             else
             {
                 result = ((IdMethodParameter) idMethodParams.get(0)).getValue();
             }
         }
         return result;
     }
 
     /***
      * Returns a List containing all the indices in the table
      *
      * @return A List containing all the indices
      */
     public List getIndices()
     {
         return indices;
     }
 
     /***
      * Returns a List containing all the UKs in the table
      *
      * @return A List containing all the UKs
      */
     public List getUnices()
     {
         return unices;
     }
 
     /***
      * Returns a specified column.
      *
      * @param name name of the column
      * @return Return a Column object or null if it does not exist.
      */
     public Column getColumn(String name)
     {
         return (Column) columnsByName.get(name);
     }
 
     /***
      * Returns a specified column.
      *
      * @param javaName java name of the column
      * @return Return a Column object or null if it does not exist.
      */
     public Column getColumnByJavaName(String javaName)
     {
         return (Column) columnsByJavaName.get(javaName);
     }
 
     /***
      * Return the first foreign key that includes col in it's list
      * of local columns.  Eg. Foreign key (a,b,c) refrences tbl(x,y,z)
      * will be returned of col is either a,b or c.
      *
      * @param col column name included in the key
      * @return Return a Column object or null if it does not exist.
      */
     public ForeignKey getForeignKey(String col)
     {
         ForeignKey firstFK = null;
         for (Iterator iter = foreignKeys.iterator(); iter.hasNext();)
         {
             ForeignKey key = (ForeignKey) iter.next();
             if (key.getLocalColumns().contains(col))
             {
                 if (firstFK == null)
                 {
                     firstFK = key;
                 }
                 else
                 {
                     //System.out.println(col+" is in multiple FKs.  This is not"
                     //                   + " being handled properly.");
                     //throw new IllegalStateException("Cannot call method if " +
                     //    "column is referenced multiple times");
                 }
             }
         }
         return firstFK;
     }
 
     /***
      * Returns true if the table contains a specified column
      *
      * @param col the column
      * @return true if the table contains the column
      */
     public boolean containsColumn(Column col)
     {
         return columnList.contains(col);
     }
 
     /***
      * Returns true if the table contains a specified column
      *
      * @param name name of the column
      * @return true if the table contains the column
      */
     public boolean containsColumn(String name)
     {
         return (getColumn(name) != null);
     }
 
     /***
      * Set the parent of the table
      *
      * @param parent the parant database
      */
     public void setDatabase(Database parent)
     {
         tableParent = parent;
     }
 
     /***
      * Get the parent of the table
      *
      * @return the parant database
      */
     public Database getDatabase()
     {
         return tableParent;
     }
 
     /***
      * Flag to determine if code/sql gets created for this table.
      * Table will be skipped, if return true.
      * @return value of forReferenceOnly.
      */
     public boolean isForReferenceOnly()
     {
         return forReferenceOnly;
     }
 
     /***
      * Flag to determine if code/sql gets created for this table.
      * Table will be skipped, if set to true.
      * @param v  Value to assign to forReferenceOnly.
      */
     public void setForReferenceOnly(boolean  v)
     {
         this.forReferenceOnly = v;
     }
 
     /***
      * Returns a XML representation of this table.
      *
      * @return XML representation of this table
      */
     public String toString()
     {
         StringBuffer result = new StringBuffer();
 
         result.append ("<table name=\"")
               .append(name)
               .append('\"');
 
         if (javaName != null)
         {
             result.append(" javaName=\"")
                   .append(javaName)
                   .append('\"');
         }
 
         if (idMethod != null)
         {
             result.append(" idMethod=\"")
                   .append(idMethod)
                   .append('\"');
         }
 
         if (skipSql)
         {
             result.append(" skipSql=\"")
                   .append(new Boolean(skipSql))
                   .append('\"');
         }
 
         if (abstractValue)
         {
             result.append(" abstract=\"")
                   .append(new Boolean(abstractValue))
                   .append('\"');
         }
 
         if (baseClass != null)
         {
             result.append(" baseClass=\"")
                   .append(baseClass)
                   .append('\"');
         }
 
         if (basePeer != null)
         {
             result.append(" basePeer=\"")
                   .append(basePeer)
                   .append('\"');
         }
 
         result.append(">\n");
 
         if (columnList != null)
         {
             for (Iterator iter = columnList.iterator(); iter.hasNext();)
             {
                 result.append(iter.next());
             }
         }
 
         if (foreignKeys != null)
         {
             for (Iterator iter = foreignKeys.iterator(); iter.hasNext();)
             {
                 result.append(iter.next());
             }
         }
 
         if (idMethodParameters != null)
         {
             Iterator iter = idMethodParameters.iterator();
             while (iter.hasNext())
             {
                 result.append(iter.next());
             }
         }
 
         result.append ("</table>\n");
 
         return result.toString();
     }
 
     /***
      * Returns the collection of Columns which make up the single primary
      * key for this table.
      *
      * @return A list of the primary key parts.
      */
     public List getPrimaryKey()
     {
         List pk = new ArrayList(columnList.size());
 
         Iterator iter = columnList.iterator();
         while (iter.hasNext())
         {
             Column col = (Column) iter.next();
             if (col.isPrimaryKey())
             {
                 pk.add(col);
             }
         }
         return pk;
     }
 
     /***
      * Determine whether this table has a primary key.
      *
      * @return Whether this table has any primary key parts.
      */
     public boolean hasPrimaryKey()
     {
         return (getPrimaryKey().size() > 0);
     }
 
     /***
      * Returns all parts of the primary key, separated by commas.
      *
      * @return A CSV list of primary key parts.
      */
     public String printPrimaryKey()
     {
         return printList(columnList);
     }
 
     /***
      * Returns the elements of the list, separated by commas.
      *
      * @param list a list of Columns
      * @return A CSV list.
      */
     private String printList(List list)
     {
         StringBuffer result = new StringBuffer();
         boolean comma = false;
         for (Iterator iter = list.iterator(); iter.hasNext();)
         {
             Column col = (Column) iter.next();
             if (col.isPrimaryKey())
             {
                 if (comma)
                 {
                     result.append(',');
                 }
                 else
                 {
                     comma = true;
                 }
                 result.append(col.getName());
             }
         }
         return result.toString();
     }
 }