我的测试项目：

结构图：

DBHleper类代码：

package com.avin.android;

import android.content.ContentValues;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;

public class DBHelper extends SQLiteOpenHelper {

public static final int VERSION = 1;

/**
* 作为SQLiteOpenHelper子类必须有的构造方法
* @param context
* @param name 数据库名字
* @param factory
* @param version
*/
public DBHelper(Context context, String name, CursorFactory factory,
int version) {
super(context, name, factory, version);
Log.d("Avin","this is dbhelper 4 elements");
// TODO Auto-generated constructor stub
}

public DBHelper(Context context,String name, int version){
this(context,name,null,version);
Log.d("Avin","this is dbhelper 3 elements");
}
public DBHelper(Context context,String name){
this(context,name,VERSION);
Log.d("Avin","this is dbhelper 2 elements");
}
@Override
/**
* 第一次创建数据库的时候调用，而且是得到readableDatabase或者writeDatabase时才执行
*/
public void onCreate(SQLiteDatabase db) {
// TODO Auto-generated method stub

db.execSQL("create table floats(id integer primary key autoincrement ,flt_cand text not null ,flt_key text)");
Log.d("Avin","floats created...");

}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// TODO Auto-generated method stub

}

}