通过输入的内容来判断数据库里面是否存在，我的代码是这样写的，查询的时候判断不了

Question

public boolean findName(String user) {
    Cursor cursor = null;
    try{
    String str = "select user from Myphoneinfo where user=?";
    SD=db.getReadableDatabase();
    cursor = SD.rawQuery(str, new String[]{user});
    while (cursor.moveToNext() ) {
   return true;
    }
    }catch(Exception e)
    {
        e.printStackTrace();
    }finally
    {
        if(cursor!=null)
        {
            cursor.close();
        }
        SD.close();
    }
    return true;
}