android 数据库

public class DataBaseHelper extends SQLiteOpenHelper {
//数据库名字
private final static String DB_NAME="mydb_name";
//表名
private final static String TABLE_NAME="mytv";
private final static int version=2;
public DataBaseHelper(Context context) {
super(context, DB_NAME, null, version);
// TODO Auto-generated constructor stub
}
/*
* 启动时建表,三个字段，name，mac，code
* @see android.database.sqlite.SQLiteOpenHelper#onCreate(android.database.sqlite.SQLiteDatabase)
*/
@Override
public void onCreate(SQLiteDatabase arg0) {
// TODO Auto-generated method stub
String sql="create table mytv(name varchar(20),mac varchar(50),code varchar(200));";
arg0.execSQL(sql);
}


@Override
public void onUpgrade(SQLiteDatabase arg0, int arg1, int arg2) {
// TODO Auto-generated method stub


}
/*
* 添加数据
*/
public long insert(TVItem tv){
if(tv==null){
return -1;
}
SQLiteDatabase db=getWritableDatabase();//获取可写的数据库

//ContentValues类似于map，存储的是键值对
ContentValues values = new ContentValues();
values.put("name", tv.getName());
values.put("mac", tv.getMac());
values.put("code", tv.getCode());
return db.insert(TABLE_NAME, null, values);
}
/*
* 删除数据
*/
public int delete(String name){
SQLiteDatabase db=getWritableDatabase();
return db.delete(TABLE_NAME, "name=?", new String[]{name});
}
/*
* 更新记录
*/
public int update(String name,TVItem tv){
SQLiteDatabase db=getWritableDatabase();
ContentValues values=new ContentValues();
values.put("name", tv.getName());
values.put("mac", tv.getMac());
values.put("code", tv.getCode());
return db.update(TABLE_NAME, values, "name=?", new String[]{name});
}
/*
* 查询
*/
public Cursor select(){
SQLiteDatabase db=getReadableDatabase();
//参数分别是表名，查询的字段，查询条件（两个参数），分组，分组条件having，排序
return db.query(TABLE_NAME, new String[]{"name","mac","code"}, null, null, null, null, null);
}

}

其他地方调用查询数据时、

Cursor cursor=db.select();
while(cursor.moveToNext()){

String name=cursor.getString(cursor.getColumnIndex("name"));
}