20151102adonet2

实现增删改查

ExecuteNonQuery:执行增删改语句,返回值为该命令所影响的行数.

ExecuteReader:执行查询,并返回 一个DataReader对象.

ExecuteScalar:执行查询,返回查询数.(删除修改时判断记录是否存在)

string strSql = string.Format("select count(*) from RNews where NewsId={0}", newsId);
using (con=new SqlConnection(strCon))
{con.Open();using (cmd=new SqlCommand(strSql,con)){if (Convert.ToInt32(cmd.ExecuteScalar().ToString()) == 0)//获取结果集数据,如果没有值就返回0 删除之前判断ID是否存在
        {Response.Write("<script>alert('这条新闻不存在')</script>");return;}else{string s = string.Format("delete RNews where NewsId={0}",newsId);using (cmd=new SqlCommand(s,con)){cmd.ExecuteNonQuery();}}}}
BindNews();
Response.Write("<script>alert('新闻删除成功')</script>");

using (con=new SqlConnection(strCon))
{con.Open();string strSql = GetSql();cmd = new SqlCommand(strSql,con); using(read=cmd.ExecuteReader()) { if (read.HasRows) { gvRNews.DataSource = read; gvRNews.DataBind(); } else { gvRNews.DataSource = null; gvRNews.DataBind(); } } }