Quadcap Embeddable Database

com/quadcap/jdbc/ResultSetMetaData.java

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package com.quadcap.jdbc;

/* Copyright 1999 - 2003 Quadcap Software.  All rights reserved.
 *
 * This software is distributed under the Quadcap Free Software License.
 * This software may be used or modified for any purpose, personal or
 * commercial.  Open Source redistributions are permitted.  Commercial
 * redistribution of larger works derived from, or works which bundle
 * this software requires a "Commercial Redistribution License"; see
 * http://www.quadcap.com/purchase.
 *
 * Redistributions qualify as "Open Source" under  one of the following terms:
 *   
 *    Redistributions are made at no charge beyond the reasonable cost of
 *    materials and delivery.
 *
 *    Redistributions are accompanied by a copy of the Source Code or by an
 *    irrevocable offer to provide a copy of the Source Code for up to three
 *    years at the cost of materials and delivery.  Such redistributions
 *    must allow further use, modification, and redistribution of the Source
 *    Code under substantially the same terms as this license.
 *
 * Redistributions of source code must retain the copyright notices as they
 * appear in each source code file, these license terms, and the
 * disclaimer/limitation of liability set forth as paragraph 6 below.
 *
 * Redistributions in binary form must reproduce this Copyright Notice,
 * these license terms, and the disclaimer/limitation of liability set
 * forth as paragraph 6 below, in the documentation and/or other materials
 * provided with the distribution.
 *
 * The Software is provided on an "AS IS" basis.  No warranty is
 * provided that the Software is free of defects, or fit for a
 * particular purpose.  
 *
 * Limitation of Liability. Quadcap Software shall not be liable
 * for any damages suffered by the Licensee or any third party resulting
 * from use of the Software.
 */

import java.sql.SQLException;

import com.quadcap.sql.Column;
import com.quadcap.sql.Cursor;
import com.quadcap.sql.Tuple;

import com.quadcap.sql.types.Type;

import com.quadcap.util.Debug;

/**
 * This class implements the <code>java.sql.ResultSetMetaData</code>
 * interface, which provides a mechanism to obtain information about
 * the columns in a <code>ResultSet</code> object.
 *
 * @author Stan Bailes
 */
public class ResultSetMetaData implements java.sql.ResultSetMetaData {
    Cursor                              cursor;

    /**
     * @deprecated
     */
    public ResultSetMetaData(Cursor cursor) {
        this.cursor = cursor;
    }
    
    /**
     * QED doesn't support catalogs.
     */
    public String getCatalogName(int column) throws SQLException {
        return "";
    }

    /**
     * Return the fully qualified class name of the Java class to which
     * the specified column will be mapped
     *
     * @param column the column number
     * @return the column's class name
     * @exception SQLException may be thrown
     */
    public String getColumnClassName(int column) throws SQLException {
        return getType(column).getJDBCClassName();
    }
    
    /**
     * Return the number of columns in the <code>ResultSet</code>.
     *
     * @return the number of columns in the <code>ResultSet</code>.
     * @exception SQLException may be thrown
     */
    public int getColumnCount() throws SQLException {
        return cursor.getColumnCount();
    }
    
    /**
     * Return the normal maximum width in characters of the values in
     * the specified column
     *
     * @param column the column number
     * @return the maximum display size of a value in this column
     * @exception SQLException may be thrown
     */
    public int getColumnDisplaySize(int column) throws SQLException {
        Column col = cursor.getColumn(column);
        int w2;
        if (col.getType() != null) {
            w2 = col.getType().getDisplayWidth();
        } else {
            w2 = col.getShortName().length();
        }
        return w2;
    }
    
    /**
     * Return the shortest possible name for this column, such that the
     * name is unique within this <code>ResultSet</code> object.  
     *
     * @param column the column number
     * @return the column label
     * @exception SQLException may be thrown
     */
    public String getColumnLabel(int column) throws SQLException {
        return cursor.getColumn(column).getShortName();
    }
    
    /**
     * Return the shortest possible name for this column, such that the
     * name is unique within this <code>ResultSet</code> object.  
     *
     * @param column the column number
     * @return the column name
     * @exception SQLException may be thrown
     */
    public String getColumnName(int column) throws SQLException {
        return cursor.getColumn(column).getShortName();
    }
    
    /**
     * Return the JDBC type of this column
     *
     * @param column the column number
     * @return the column's JDBC type
     * @exception SQLException may be thrown
     */
    public int getColumnType(int column) throws SQLException {
        return getType(column).getJDBCType();
    }
    
    /**
     * Return the SQL type name of this column
     *
     * @param column the column number
     * @return the column's SQL type
     * @exception SQLException may be thrown
     */
    public String getColumnTypeName(int column) throws SQLException {
        return getType(column).getTypeName();
    }
    
    /**
     * Return the maximum precision of this column, or -1 if this column
     * is not a numeric type.
     *
     * @param column the column number
     * @return the column's maximum precision
     * @exception SQLException may be thrown
     */
    public int getPrecision(int column) throws SQLException {
        return getType(column).getPrecision();
    }
    
    /**
     * Return the scale of this column, or -1 if this column is not
     * a numeric type
     *
     * @param column the column number
     * @return the column's scale
     * @exception SQLException may be thrown
     */
    public int getScale(int column) throws SQLException {
        return getType(column).getScale();
    }
    
    /**
     * Return the schema name for the table from which this column
     * is derived.  This function works for normal columns, but
     * returns the empty string for computed columns.
     *
     * @param column the column number
     * @return the column's table's schema's name
     * @exception SQLException may be thrown
     */
    public String getSchemaName(int column) throws SQLException {
        String s = cursor.getColumn(column).getName();
        int idx = s.indexOf('.');
        if (idx >= 0) {
            return s.substring(0, idx);
        } else {
            return "";
        }
    }
    
    /**
     * Return name of the table from which this column is derived.
     *
     * @param column the column number
     * @return the column's table's name
     * @exception SQLException may be thrown
     */
    public String getTableName(int column) throws SQLException {
        String ret = "";
        Tuple table = cursor.getColumn(column).getRelation();
        if (table != null) ret = table.getName();
        return ret;
    }
    
    /**
     * Return <code>true</code> if this is an auto-increment type.
     *
     * @param column the column number
     * @return false
     * @exception SQLException may be thrown
     */
    public boolean isAutoIncrement(int column) throws SQLException {
        Column col = cursor.getColumn(column);
        return cursor.getColumn(column).isAutoIncrement();
    }
    
    /**
     * Return <code>true</code> if this column is case-sensitive.
     * QED always returns <code>false</code>.
     *
     * @param column the column number
     * @return false
     * @exception SQLException may be thrown
     */
    public boolean isCaseSensitive(int column) throws SQLException {
        return getType(column).isCaseSensitive();
    }
    
    /**
     * Return <code>true</code> if this column is a cash value.
     * QED always returns <code>false</code>.
     *
     * @param column the column number
     * @return false
     * @exception SQLException may be thrown
     */
    public boolean isCurrency(int column) throws SQLException {
        return getType(column).isCurrency();
    }
    
    /**
     * Return <code>true</code> if this column is definitely
     * writable
     *
     * @param column the column number
     * @return true if this column is writable
     * @exception SQLException may be thrown
     */
    public boolean isDefinitelyWritable(int column) throws SQLException {
        return cursor.isWritable(column); 
    }
    
    /**
     * Return the JDBC 'nullability' state for this column
     *
     * @param column the column number
     * @return if this column can contain <code>NULL</code>s
     * @exception SQLException may be thrown
     */
    public int isNullable(int column) throws SQLException {
        return cursor.getColumn(column).getNullable();
    }
    
    /**
     * Return <code>true</code> if this column is not writable
     *
     * @param column the column number
     * @return true if this column is read-only
     * @exception SQLException may be thrown
     */
    public boolean isReadOnly(int column) throws SQLException {
        return !cursor.isWritable(column);
    }
    
    /**
     * Return true if the column can be used in a <code>WHERE</code>
     * clause.  QED always returns <code>true</code>
     *
     * @param column the column number
     * @return true
     * @exception SQLException may be thrown
     */
    public boolean isSearchable(int column) throws SQLException {
        return true;
    }
    
    /**
     * Return true if this column contains a signed number.  In QED, this
     * is true for all numeric types and for intervals.
     *
     * @param column the column number
     * @return true if this column contains a signed number
     * @exception SQLException may be thrown
     */
    public boolean isSigned(int column) throws SQLException {
        return getType(column).isSigned();
    }
    
    /**
     * Return <code>true</code> if this column is writable.
     *
     * @param column the column number
     * @return true if this column is writable.
     * @exception SQLException may be thrown
     */
    public boolean isWritable(int column) throws SQLException {
        return cursor.isWritable(column);
    }

    private Type getType(int column) throws SQLException {
        Type t = cursor.getColumn(column).getType();
        return t;
    }
    
}