Question

ASP.NET C# 的数据更新（update）问题

做了一个管理员更新数据的代码，求改正update按钮的代码
第一个select 按钮是根据条件搜索数据库，并且把数据库中对应的值显示到下面四个textbox中。（这个运行成功）
第二个update的按钮是将新输入在下面四个textbox 中的数据更新到数据库中。我内个代码我输入的数据进去不了数据库，求大神改正！

void Button1_Click(object sender, EventArgs e) {
string strconnect;
strconnect = "Provider=microsoft.jet.oledb.4.0;";
strconnect += "data source=" + MapPath("uktrip.mdb");
strconnect += ";persist security info=false";
OleDbConnection DBconnection = new OleDbConnection(strconnect);
OleDbCommand DBcommand = new OleDbCommand("select hot_city, hot_name, hot_star, hot_link FROM hotels WHERE hot_city like '%"+TextBox1.Text.Trim()+"%' ", DBconnection);
DBconnection.Open();
OleDbDataReader reader;
reader = DBcommand.ExecuteReader();

if (reader.Read())
{
TextBox2.Text = reader["hot_name"].ToString();
TextBox3.Text = reader["hot_star"].ToString();
TextBox4.Text = reader["hot_city"].ToString();
TextBox5.Text = reader["hot_link"].ToString();
}
Button2.Enabled = true;
reader.Close();
DBconnection.Close();
}

void Button2_Click(object sender, EventArgs e) {
string strconnect;
strconnect = "Provider=microsoft.jet.oledb.4.0;";
strconnect += "data source=" + MapPath("uktrip.mdb");
strconnect += ";persist security info=false";
OleDbConnection DBconnection = new OleDbConnection(strconnect);
OleDbCommand DBcommand = new OleDbCommand("update hotels set hot_city='"+TextBox4.Text+"', hot_name='"+TextBox2.Text+"' , hot_star='"+TextBox2.Text+"', hot_link='"+TextBox4.Text+"' WHERE hot_city=@hot_city ", DBconnection);
DBconnection.Open();
DBconnection.Close();
}

Answer 1

　　void Button2_Click(object sender, EventArgs e)

　　{

　　string city = TextBox4.Text.Trim().Replace(",", "");

　　if (city == "") { Response.Write("<script>alert('city is not null ');</script>"); return; }

　　string strconnect;

　　strconnect = "Provider=microsoft.jet.oledb.4.0;";

　　strconnect += "data source=" + MapPath("uktrip.mdb");

　　strconnect += ";persist security info=false";

　　OleDbConnection DBconnection = new OleDbConnection(strconnect);

　　string sql = "";

　　sql = " SELECT COUNT(*) FROM  hotels WHERE hot_city='" + city + "' ";

　　OleDbCommand DBcommand = new OleDbCommand();

　　DBcommand.CommandText = sql;

　　DBcommand.Connection = DBconnection;

　　DBconnection.Open();

　　int count = Convert.ToInt32(DBcommand.ExecuteScalar());

　　if (count == 0) { Response.Write("<script>alert('city is null ');</script>"); return; }

　　DBconnection.Close();

　　sql = "update hotels set hot_city=@hot_city'" + TextBox4.Text + "', hot_name=@hot_name'" + TextBox2.Text + "' , hot_star=@hot_star'" + TextBox2.Text + "', hot_link=@hot_link'" + TextBox4.Text + "' WHERE hot_city=@hot_city  ";

　　OleDbParameter[] parm = {new OleDbParameter("@hot_city",city) };

　　DBcommand.CommandText = sql;

　　DBcommand.Connection = DBconnection;

　　DBconnection.Open();

　　DBcommand.ExecuteNonQuery();

　　DBconnection.Close();

　　}

　　//写了半天也没搞明白你具体想干嘛~~~

追问

谢谢你的回答，就是只设置第二个按钮让他可以update就好了。。。我内个update有点毛病，你这个我用着　　if (city == "") { Response.Write("alert('city is not null ');"); return; }说常量有换行符。。。

追答

这个是判断文本框里有没有数据的

Answer 2

hot_city=@hot_city 这个=@hot_city 没有传值， 设置为常量

Answer 3

分享电脑常用小技巧，电脑知识，电脑技巧，电脑常见问题解决方法等，今天分享的是，4步方法解决Windows Update无法更新或更新报错，感谢粉丝们一直以来的支持

Answer 4

@hot_city 没有指定值

追问

。。。那需要怎么改？求正确的改法，谢谢~

追答

建议where条件 后 用ID 做指定。 如果非要用hot_city的话，那么 city的值就不能修改，要保持不变，这样数据库才会找到这条数据的。