Program: 74019
Project: 74019
Buggy source:
/** 
 * Execute the specified SQL statement and return the result as a string. Note that if there is no connection to the database, this will open one. The caller is responsible for calling closeConnection() after this.
 * @param sql The query.
 * @return The result as a string.
 * @exception IllegalActionException If the statement fails.
 */
public String execute(String sql) throws IllegalActionException {
  PreparedStatement statement=null;
  Connection connection=getConnection();
  try {
    if (connection == null) {
      return "String_Node_Str";
    }
    connection.setAutoCommit(false);
    statement=connection.prepareStatement(sql);
    boolean result=statement.execute();
    StringBuffer resultString=new StringBuffer();
    while (true) {
      if (result) {
        ResultSet resultSet=statement.getResultSet();
        ResultSetMetaData metaData=resultSet.getMetaData();
        int columnCount=metaData.getColumnCount();
        List<String[]> rows=new LinkedList<String[]>();
        String[] columnNames=new String[columnCount];
        int[] columnWidths=new int[columnCount];
        for (int c=0; c < columnCount; c++) {
          String columnName=metaData.getColumnName(c + 1);
          columnWidths[c]=columnName.length() + 1;
          columnNames[c]=columnName;
        }
        rows.add(columnNames);
        while (resultSet.next()) {
          String[] row=new String[columnCount];
          for (int c=0; c < columnCount; c++) {
            String value=resultSet.getString(c + 1);
            if (value == null) {
              value="String_Node_Str";
            }
            row[c]=value;
            if (value.length() > columnWidths[c]) {
              columnWidths[c]=value.length();
            }
          }
          rows.add(row);
        }
        for (        String[] row : rows) {
          for (int c=0; c < columnCount; c++) {
            resultString.append(row[c]);
            for (int i=0; i <= columnWidths[c] - row[c].length(); i++) {
              resultString.append("String_Node_Str");
            }
          }
          resultString.append("String_Node_Str");
        }
      }
 else {
        int count=statement.getUpdateCount();
        if (count != -1) {
          resultString.append("String_Node_Str" + count + "String_Node_Str");
          resultString.append("String_Node_Str");
        }
 else {
          connection.commit();
          return resultString.toString();
        }
      }
      result=statement.getMoreResults();
    }
  }
 catch (  SQLException e) {
    try {
      connection.rollback();
    }
 catch (    SQLException e1) {
    }
    return ("String_Node_Str" + e.getMessage());
  }
}

Fixed version (ground truth):
/** 
 * Execute the specified SQL statement and return the result as a string. Note that if there is no connection to the database, this will open one. The caller is responsible for calling closeConnection() after this.
 * @param sql The query.
 * @return The result as a string.
 * @exception IllegalActionException If the statement fails.
 */
public String execute(String sql) throws IllegalActionException {
  PreparedStatement statement=null;
  Connection connection=getConnection();
  try {
    if (connection == null) {
      return "String_Node_Str";
    }
    connection.setAutoCommit(false);
    statement=connection.prepareStatement(sql);
    boolean result=statement.execute();
    StringBuffer resultString=new StringBuffer();
    while (true) {
      if (result) {
        ResultSet resultSet=statement.getResultSet();
        ResultSetMetaData metaData=resultSet.getMetaData();
        int columnCount=metaData.getColumnCount();
        List<String[]> rows=new LinkedList<String[]>();
        String[] columnNames=new String[columnCount];
        int[] columnWidths=new int[columnCount];
        for (int c=0; c < columnCount; c++) {
          String columnName=metaData.getColumnName(c + 1);
          columnWidths[c]=columnName.length() + 1;
          columnNames[c]=columnName;
        }
        rows.add(columnNames);
        while (resultSet.next()) {
          String[] row=new String[columnCount];
          for (int c=0; c < columnCount; c++) {
            String value=resultSet.getString(c + 1);
            if (value == null) {
              value="String_Node_Str";
            }
            row[c]=value;
            if (value.length() > columnWidths[c]) {
              columnWidths[c]=value.length();
            }
          }
          rows.add(row);
        }
        for (        String[] row : rows) {
          for (int c=0; c < columnCount; c++) {
            resultString.append(row[c]);
            for (int i=0; i <= columnWidths[c] - row[c].length(); i++) {
              resultString.append("String_Node_Str");
            }
          }
          resultString.append("String_Node_Str");
        }
      }
 else {
        int count=statement.getUpdateCount();
        if (count != -1) {
          resultString.append("String_Node_Str" + count + "String_Node_Str");
          resultString.append("String_Node_Str");
        }
 else {
          connection.commit();
          return resultString.toString();
        }
      }
      result=statement.getMoreResults();
    }
  }
 catch (  SQLException e) {
    try {
      connection.rollback();
    }
 catch (    SQLException e1) {
    }
    return ("String_Node_Str" + e.getMessage());
  }
 finally {
    if (statement != null) {
      try {
        statement.close();
      }
 catch (      SQLException e1) {
      }
    }
  }
}