初识ASP.NET

1、 数据库连接的2种方式：
（1）Data Source=;Initial Catalog=;Integrated Security=True 不需要通过sa和密码直接登录页面
（2）<add name="take_out_system" connectionString="Data Source=USER62-PC\SQLEXPRESS;Initial Catalog=_TakeOutSystem;User Id=sa;Password=123456;"></add>
2.明码变成隐码：在相应的textbox里面多加入一行属性 TextMode="Password"(其中Password为textbox的Id)

3.类里面的一些命名规则。变量一般为_id ,_userName (下划线+小写。。后面的英语单词

大写)
方法名：一般大写字母开头

4.学会使用数据库的增删改查4条基本的语句：

增：string sql = "insert into category([name]) values(@caName)";

public bool AddComment(Comment c)
{
string sql = "insert into comment(newsid,[content],userip) values(@newsID,@content,@userIP)";
SqlParameter[] paras = new SqlParameter[] { new SqlParameter("@newsID",c.NewsId),new SqlParameter("@content",c.Content),new SqlParameter("@userIP",c.UserIP)};
if (sqlhelper.ExecuteNonQuery(sql, paras,CommandType.Text) > 0)
{
return true;
}
return false;
}

insertinto[table]([字段])values(@a)

删：string sql = "Delete from category whereid=@id";

public bool Delete(int id)
{
string sql = "delete comment where id=@id";
SqlParameter[] paras = new SqlParameter[] {new SqlParameter("@id",id) };
if (sqlhelper.ExecuteNonQuery(sql,paras,CommandType.Text)>0)
{
return true;
}
return false;
}

改：string sql = "update category set [name]=@caName whereid=@caId";

public bool Update(Category ca)
{
bool flag = false;
string sql = "update category set [name]=@caName where id=@caId";
SqlParameter[] paras = new SqlParameter[]
{
new SqlParameter("@caName",ca.Name),new SqlParameter("@caId",ca.Id)
};

if (sqlhelper.ExecuteNonQuery(sql, paras,CommandType.Text) > 0)
{
flag = true;
}
return flag;
}

查：string sql = "select * from category whereid=@caid";

public DataTable SelectByNewsID(int newsId)
{
DataTable dt = new DataTable();
string sql = "select * from comment where newsid=@newsId";
SqlParameter[] paras=new SqlParameter[]{new SqlParameter("@newsId",newsId)};
dt=sqlhelper.ExecuteQuery(sql, paras,CommandType.Text);
return dt;
}