/*

   Derby - Class org.apache.derby.iapi.sql.ResultDescription

   Licensed to the Apache Software Foundation (ASF) under one or more
   contributor license agreements.  See the NOTICE file distributed with
   this work for additional information regarding copyright ownership.
   The ASF licenses this file to you 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.

 */

package org.apache.derby.iapi.sql;

/**
 * The ResultDescription interface provides methods to get metadata on the
 * results returned by a statement.
 *
 */

public interface ResultDescription
{
	/**
	 * Returns an identifier that tells what type of statement has been
	 * executed. This can be used to determine what other methods to call
	 * to get the results back from a statement. For example, a SELECT
	 * statement returns rows and columns, while other statements don't,
	 * so you would only call getColumnCount() or getColumnType() for
	 * SELECT statements.
	 *
	 * @return	A String identifier telling what type of statement this
	 *		is.
	 */
	String	getStatementType();	

	/**
	 * Returns the number of columns in the result set.
	 *
	 * @return	The number of columns in the result set.
	 */
	int	getColumnCount();

	/**
		Return information about all the columns.

        @return information about all the columns
	*/
	public ResultColumnDescriptor[] getColumnInfo();

    /**
     * Return the information about a single column (0-based indexing)
     *
     * @param idx The column index
     * @return The column descriptor
     */
    public  ResultColumnDescriptor  getColumnInfo( int idx );

	/**
	 * Returns a ResultColumnDescriptor for the column, given the ordiinal
	 * position of the column.
	 * NOTE - position is 1-based.
	 *
	 * @param position	The oridinal position of a column in the
	 *			ResultSet.
	 *
	 * @return		A ResultColumnDescriptor describing the
	 *			column in the ResultSet.
	 */
	ResultColumnDescriptor	getColumnDescriptor(int position);

	/**
	 * Get a new result description that has been truncated
	 * from input column number.   If the input column is
	 * 5, then columns 5 to getColumnCount() are removed.
	 * The new ResultDescription points to the same
	 * ColumnDescriptors (this method performs a shallow
	 * copy. The saved JDBC ResultSetMetaData will
     * not be copied.
	 *
	 * @param truncateFrom the starting column to remove,
	 * 1-based.
	 *
	 * @return a new ResultDescription
	 */
	public ResultDescription truncateColumns(int truncateFrom);
    
    /**
     * Set the JDBC ResultSetMetaData for this ResultDescription.
     * A ResultSetMetaData object can be saved in the statement
     * plan using this method. This only works while
     * the ResultSetMetaData api does not contain a getConnection()
     * method or a close method.
     * <BR>
     * If this object already has a saved meta data object
     * this call will do nothing.
     * Due to synchronization the saved ResultSetMetaData
     * object may not be the one passed in, ie. if two
     * threads call this concurrently, only one will be saved.
     * It is assumed the JDBC layer passes in a ResultSetMetaData
     * object based upon this.
     *
     * @param rsmd The metadata to set
     */
    public void setMetaData(java.sql.ResultSetMetaData rsmd);
    
    /**
     * Get the saved JDBC ResultSetMetaData. Will return
     * null if setMetaData() has not been called on this
     * object. The caller then should manufacture a
     * ResultSetMetaData object and pass it into setMetaData.
     *
     * @return the metadata
     */
    public java.sql.ResultSetMetaData getMetaData();
    
    /**
     * Return the position of the column matching the
     * passed in names following the JDBC rules for
     * ResultSet.getXXX and updateXXX.
     * Rules are the matching is case insensitive
     * and the insensitive name matches the first
     * column found that matches (starting at postion 1).
     * @param name The column name
     * @return Position of the column (1-based), -1 if no match.
     */
    public int findColumnInsenstive(String name);
}
