偶也不知道算不算，反正我自己随时写的用，很粗浅的，适合跟我一样的新手收藏，指不定就用得上呢！

一组是我这两天写留言本的
另组是以前vs2003写投票用的

高手看见的话，麻烦把好的解决方案说下，谢谢哦！！新手的话，共同学习了！！

--------下面是我最近写个留言本用的------------
    public static oledbconnection con()
    {//数据库连接类
        oledbconnection con = new oledbconnection(configurationmanager.connectionstrings["book"].connectionstring);
        return con;
    }
    public static bool insert(string que)
    { //根据传进来的ｓｑｌ语句执行插入操作
        oledbconnection con = odb.con();
        con.open();
        oledbcommand cmd = new oledbcommand(que,con);
        int count = convert.toint32(cmd.executenonquery());
        if (count > 0)
            return true;
        else
            return false;
        con.close();
    }
    public static datatable ds(string que)
    {//返回一个装载了sql制定留言的数据表，
        oledbconnection con = odb.con();
        oledbdataadapter oda = new oledbdataadapter();
        oda.selectcommand=new oledbcommand(que,con);
        dataset ds = new dataset();
        oda.fill(ds,"thc");
        return ds.tables["thc"];
        con.close();
    }
    public static bool img(string que)
    {//根据传来的条件查询该项是否有内容，有就返回true
        oledbconnection con = odb.con();
        con.open();
        oledbcommand cmd = new oledbcommand(que,con);
        if (cmd.executescalar().tostring() != "")
            return true;
        else
            return false;
        con.close();
    }
    public static string scr(string que)
    {//同样是根据传来的ｓｑｌ语句返回一个字段的值，我不太喜欢把ｓｑｌ语句做在内中，感觉不灵活
        oledbconnection con = odb.con();
        con.open();
        oledbcommand cmd = new oledbcommand(que,con);
        return cmd.executescalar().tostring();
    }

-----------下面是以前2003的时候用的----------
public static sqlconnection con()
        {//（静态）初始化链接，因为数据库路径在web.config文件里面，所以这里返回的是哪个字符串,这是ｖｓ２００３的数据库连接初始实例
            sqlconnection con=new sqlconnection(system.configuration.configurationsettings.appsettings["con"]);
            return con;
        }
        public static bool chklog(string name,string pwd)
        {//判断数据库里是否存在这个用户，返回真或则假
            sqlconnection con=db.con();
            con.open();
            sqlcommand cmd=new sqlcommand("select count(*) from admin where name="+name+" and pwd="+pwd+"",con);
            int count=convert.toint32(cmd.executescalar());
            if(count>0)
            {
                return true;
            }
            else
            {
                return false;
            }
        }
        public static string chkqx(string name,string pwd)
        {//判断当前用户的权限，并返回权限
            sqlconnection con=db.con();
            con.open();
            sqlcommand cmd=new sqlcommand("select qx from admin where name="+name+" and pwd="+pwd+"",con);
            string qx=convert.tostring(cmd.executescalar());
            return qx;
        }
        public static datatable fill(string query)
        {//根据传来的ｓｑｌ语句查询出数据并填充一个表给查询对象
            sqlconnection con=db.con();
            sqldataadapter sda=new sqldataadapter();
            sda.selectcommand=new sqlcommand(query,con);
            dataset ds=new dataset();
            sda.fill(ds,"vote");
            return ds.tables["vote"];
          
        }
        public static string title(int id)
        {//(静态)根据传来的id返回该投票项标题
            sqlconnection con=db.con();
            con.open();
            sqlcommand cmd=new sqlcommand("select xiang from votemaster where id="+id+"",con);
            return cmd.executescalar().tostring();
        }
        public static void delete(string query)
        {//(静态)执行指定的删除行为
            sqlconnection con=db.con();
            con.open();
            sqlcommand cmd=new sqlcommand(query,con);
            cmd.executenonquery();
        }
        public static void update(string query)
        {//(静态)执行指定的更新行为
            sqlconnection con=db.con();
            con.open();
            sqlcommand cmd=new sqlcommand(query,con);
            cmd.executenonquery();
        }
        public static int cid(string query)
        {//（静态）根据执行的语句查询出当前数据库最新的一个ｉｄ
            sqlconnection con=db.con();
            con.open();
            sqlcommand cmd=new sqlcommand(query,con);
            int id=convert.toint32(cmd.executescalar());
            return id;
        }
        public static bool insert(string query)
        {//插入操作
            sqlconnection con=db.con();
            con.open();
            sqlcommand cmd=new sqlcommand(query,con);           
            int count=convert.toint32(cmd.executenonquery());
            if(count>0)
            {
                return true;
            }
            else
            {
                return false;
            }
        }
        public static int typ(int id)
        {//根据出来的ｉｄ，返回该ｉｄ所属于的投票属于多选还是单选
            sqlconnection con=db.con();
            con.open();
            sqlcommand cmd=new sqlcommand("select typ from votemaster where id="+id+"",con);
            int typ=convert.toint32(cmd.executescalar());
            return typ;
        }
        public static string count()
        {//返回总访问人数
            sqlconnection con=db.con();
            con.open();
            sqlcommand cmd=new sqlcommand("select coun from countline",con);
            string count=cmd.executescalar().tostring();
            return count;
        }
        public static string rengyi(string query)
        {//查询任意单字段，返回字段值的一个静态方法
            sqlconnection con=db.con();
            con.open();
            sqlcommand cmd=new sqlcommand(query,con);
            return cmd.executescalar().tostring();
        }
        public static bool vlog(string query)
        {//查询任意单字段,返回真与假的一个静态方法
            sqlconnection con=db.con();
            con.open();
            sqlcommand cmd=new sqlcommand(query,con);
            int count=convert.toint32(cmd.executescalar());
            if(count>0)
            {
                return true;
            }
            else
            {
                return false;
            }
        }
http://thcjp.cnblogs.com/archive/2006/06/18/428775.html