rowsequence.java

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package MyNa.utils;

import java.sql.*;
import java.util.Hashtable;

/* the RowSequence provides access to a ResultSet as
an sequence of Env (extended Hashtable) structures: 
with RowSequence rS,
  rS.next() will  shift to the next Env and return true,
reading and processing a row -- or fail.
and rS.getRow() will return the current Env. 

*/
public class RowSequence {
  ResultSet theResultSet; Env theEnv;
  String [] theColumnLabels; String [] theColumnTypes;
  String [] theColumnValues;
  int theNumberOfColumns;

public RowSequence(ResultSet R,Env queryInfo)
    throws SQLException{
  theResultSet=R; theEnv=queryInfo;
  if(R==null){
    theColumnLabels=null;
    theColumnTypes=null;
    theColumnValues=null;
    theNumberOfColumns=0;
   }else{
  theColumnLabels=MiscDB.resultSetLabels(R);
  theColumnTypes=MiscDB.resultSetTypes(R);
  theNumberOfColumns=theColumnLabels.length;
  theColumnValues=new String[theNumberOfColumns];
  theEnv.put("NumberOfColumns",""+theNumberOfColumns);
  theEnv.put("FieldName",theColumnLabels);
  theEnv.put("FieldType",theColumnTypes);
  theEnv.put("FieldValue",theColumnValues);
  for(int i=1;i<=theNumberOfColumns;i++)
    theEnv.put("FieldName"+i,theColumnLabels[i-1]);
  }
}
public RowSequence(ResultSet R)
    throws SQLException{
  this(R,new Env());
}

public boolean next(){
  if(theResultSet==null)return false;
  try{
    if(!theResultSet.next()){
      theResultSet.close();
      theResultSet=null;
      return false;
      }
    for(int i=1;i<=theNumberOfColumns;i++){
      String S=theResultSet.getString(i);
      theColumnValues[i-1]=S;
      theEnv.put(theColumnLabels[i-1],S);
      theEnv.put("FieldValue"+i,S);
      }
    return true;
}catch(Exception E){}
  return false;
}
public Env getRow(){
  return theEnv;
}

// tools for inheritance, e.g. pruning a RowSequence.

public void initFromRowSequence(RowSequence re){ // a shallow copy
  this.theResultSet=re.theResultSet;
  this.theEnv=re.theEnv;
  this.theColumnLabels=re.theColumnLabels;
  this.theColumnTypes=re.theColumnTypes;
  this.theColumnValues=re.theColumnValues;
  this.theNumberOfColumns=re.theNumberOfColumns;
}
public RowSequence(){} // a do-nothing empty constructor

}