basetoken.java

用JAVA实现了,将DB装入内存,内存由DBMS控制,实现简单数据库的创建、数据表的创建、记录插入、查询以及表的删除。

package org.kdb.parser;

import java.util.HashMap;
import java.util.Map;

/**
 * User: lijunzhuang
 * Date: 2007-11-21
 * Time: 14:30:24
 */
public class BaseToken {
    private static final String SELECT = "SELECT";
    private static final String DELETE = "DELETE";
    private static final String INSERT = "INSERT";
    private static final String USE = "USE";
    private static final String CREATE = "CREATE";
    private static final String DATABASE = "DATABASE";
    private static final String TABLE = "TABLE";
    private static final String WHERE = "WHERE";
    private static final String FROM = "FROM";
    private static final String VALUES = "VALUES";
    private static final String DESC = "DESC";
    private static Map<String, Integer> tokens = null;

    static {
        tokens = new HashMap<String, Integer>(20);
        tokens.put(SELECT, 1);
        tokens.put(DELETE, 2);
        tokens.put(INSERT, 3);
        tokens.put(USE, 4);
        tokens.put(CREATE, 5);
        tokens.put(DATABASE, 6);
        tokens.put(TABLE, 7);
        tokens.put(WHERE, 8);
        tokens.put(FROM, 9);
        tokens.put(VALUES, 10);
        tokens.put(DESC, 11);
    }

    public static int getKey(String tokenName) {
        return tokens.get(tokenName);
    }

}