[英]SQL Server C# can't insert in to the database
问题:
System.Data.dll中发生类型'System.Data.SqlClient.SqlException'的异常,但未在用户代码中处理
附加信息:
参数化查询(@name nvarchar(7), @height float, @heightscale nvarchar(5), @weigh
期望参数@monthDis
,未提供)
我的代码:
public partial class Step3 : System.Web.UI.Page
{
protected void Button1_Click(object sender, EventArgs e)
{
SqlConnection c;
string str = "Data Source =(LocalDB)\\MSSQLLocalDB;";
str += "AttachDbFilename=|DataDirectory|\\DinoData.mdf;";
str += "Integrated Security= True";
c = new SqlConnection(str);
if (Page.IsValid == true)
{
Session["yourlocation"] = ddlcountry.SelectedItem.Text;
Session["dayborn"] = DDLborn.SelectedItem.Text;
Session["monthborn"] = ddlmonthborn.SelectedItem.Text;
Session["yearborn"] = txtyar.Text;
Session["yourEmail"] = txtemail.Text;
Session["Gender"] = rbgendere.SelectedItem.Text;
Session["YourName"] = txtName.Text;
Session["YourLastName"] = txtLName.Text;
SqlCommand NewUser = new SqlCommand("INSERT INTO [DinoTable] VALUES(@name, @height, @heightscale, @weight, @weightscale, @diet, @status, @locationDis, @dayDis, @monthDis, @yearDis, @yourlocation, @dayborn, @monthborn, @yearborn, @Gender, @yourEmail, @yoname, @lastname);", c);
NewUser.Connection = c;
NewUser.Parameters.AddWithValue("@name", (string) Session["Name"]);
NewUser.Parameters.AddWithValue("@height", Convert.ToDouble(Session["Height"]));
NewUser.Parameters.AddWithValue("@heightscale", (string)Session["HeightScale"]);
NewUser.Parameters.AddWithValue("@weight", Convert.ToDouble(Session["Weight"]));
NewUser.Parameters.AddWithValue("@weightscale", (string)Session["weightscale"]);
NewUser.Parameters.AddWithValue("@diet", (string)Session["diet"]);
NewUser.Parameters.AddWithValue("@status", (string)Session["status"]);
NewUser.Parameters.AddWithValue("@locationDis", (string)Session["locationDis"]);
NewUser.Parameters.AddWithValue("@dayDis", Convert.ToInt32(Session["dayDis"]));
NewUser.Parameters.AddWithValue("@monthDis", (string)(Session["monthDis"]));
NewUser.Parameters.AddWithValue("@yearDis", Convert.ToInt32(Session["yearDis"]));
NewUser.Parameters.AddWithValue("@yourlocation", (string)Session["yourlocation"]);
NewUser.Parameters.AddWithValue("@dayborn", Convert.ToInt32(Session["dayborn"]));
NewUser.Parameters.AddWithValue("@monthborn", (string)(Session["monthborn"]));
NewUser.Parameters.AddWithValue("@yearborn", Convert.ToInt32(Session["yearborn"]));
NewUser.Parameters.AddWithValue("@Gender", (string)Session["Gender"]);
NewUser.Parameters.AddWithValue("@yourEmail", (string)Session["yourEmail"]);
NewUser.Parameters.AddWithValue("@yoname", (string)Session["YourName"]);
NewUser.Parameters.AddWithValue("@lastname", (string)Session["YourLastName"]);
NewUser.Parameters.AddWithValue("@MoneyinMilions", 3);
c.Open();
NewUser.ExecuteNonQuery();
c.Close();
Response.Redirect("finish%20new.aspx", true);
}
}
}
谢谢大家的帮助!
查询时,未分配的会话变量将返回null
。 通过AddWithValue
作为参数传递时,它会生成您看到的错误。
如果不需要数据库中的值(它是可为空的列),则可以测试null
并使用C#合并运算符替换为DBNull.Value
:
NewUser.Parameters.AddWithValue("@monthDis", Session["monthDis"] ?? DBNull.Value);
或者,如果需要该值(NOT NULL列),则应提供默认值(或引发异常):
NewUser.Parameters.AddWithValue("@monthDis", Session["monthDis"] ?? "");
我对构建SQL参数的代码部分进行了一些细微调整(包括如果Name
为null
则抛出异常,因为这是主键):
//exit function if any required values are not specified in the Session
if (Session["Name"] == null)
{
throw new Exception("Name is a required but not specified");
}
using (SqlCommand newUser = new SqlCommand(queryString, c))
{
newUser.Parameters.AddWithValue("@name", Session["Name"]);
newUser.Parameters.AddWithValue("@height", Convert.ToDouble(Session["Height"]));
newUser.Parameters.AddWithValue("@heightscale", Session["HeightScale"] ?? "");
newUser.Parameters.AddWithValue("@weight", Convert.ToDouble(Session["Weight"]));
newUser.Parameters.AddWithValue("@weightscale", Session["weightscale"] ?? "");
newUser.Parameters.AddWithValue("@diet", Session["diet"] ?? "");
newUser.Parameters.AddWithValue("@status", Session["status"] ?? "");
newUser.Parameters.AddWithValue("@locationDis", Session["locationDis"] ?? "");
newUser.Parameters.AddWithValue("@dayDis", Convert.ToInt32(Session["dayDis"]));
newUser.Parameters.AddWithValue("@monthDis", Session["monthDis"] ?? "");
newUser.Parameters.AddWithValue("@yearDis", Convert.ToInt32(Session["yearDis"]));
newUser.Parameters.AddWithValue("@yourlocation", Session["yourlocation"] ?? "");
newUser.Parameters.AddWithValue("@dayborn", Convert.ToInt32(Session["dayborn"]));
newUser.Parameters.AddWithValue("@monthborn", Session["monthborn"] ?? "");
newUser.Parameters.AddWithValue("@yearborn", Convert.ToInt32(Session["yearborn"]));
newUser.Parameters.AddWithValue("@Gender", Session["Gender"] ?? "");
newUser.Parameters.AddWithValue("@yourEmail", Session["yourEmail"] ?? "");
newUser.Parameters.AddWithValue("@yoname", Session["YourName"] ?? "");
newUser.Parameters.AddWithValue("@lastname", Session["YourLastName"] ?? "");
newUser.Parameters.AddWithValue("@MoneyinMilions", 3);
c.Open();
newUser.ExecuteNonQuery(); //if you are not returning a result set, this is what you use. Use ExecuteQuery() if you want to return data from the DB.
c.Close();
}
此外,插入时,必须在查询字符串中将表中所有未在数据库中配置默认值的必填字段指定为参数。 在插入过程中显式列出列名也是一个好习惯:
string queryString =
"INSERT INTO [DinoTable] (DinoName, DinoHeight, Heightskale, DinoWeight, Weightskale, diet, Status, LocationDiscovery, DayDiscovery, monthDiscovery, yearDiscovery, YourLocation, DayBorn, monthBorn, YearBorn, YourGender, YourEmail, YourName, YourLastName, MoneyinMilions) VALUES(@name, @height, @heightscale, @weight, @weightscale, @diet, @status, @locationDis, @dayDis, @monthDis, @yearDis, @yourlocation, @dayborn, @monthborn, @yearborn, @Gender, @yourEmail, @yoname, @lastname, @MoneyinMilions);";
您在SQL查询中缺少@MoneyinMillions。
SqlCommand NewUser = new SqlCommand("INSERT INTO [DinoTable] VALUES(@name,
@height, @heightscale, @weight, @weightscale, @diet, @status, @locationDis,
@dayDis, @monthDis, @yearDis, @yourlocation, @dayborn, @monthborn, @yearborn,
@Gender, @yourEmail, @yoname, @lastname, @MoneyinMillions);", c);
我很确定您的问题就是您的查询。
SqlCommand NewUser = new SqlCommand("INSERT INTO [DinoTable] VALUES(@name, @height, @heightscale, @weight, @weightscale, @diet, @status, @locationDis, @dayDis, @monthDis, @yearDis, @yourlocation, @dayborn, @monthborn, @yearborn, @Gender, @yourEmail, @yoname, @lastname);", c);
您正在向查询中添加参数,但该参数很可能为null。 NewUser.Parameters.AddWithValue("@monthDis", (string)(Session["monthDis"]));
您需要按照@DevTony的建议在传递会话变量之前检查会话变量是否为null。
protected void Button1_Click(object sender, EventArgs e)
{
//when using sql connection objects, be sure to enclose them in a using block to properly dispose of resources.
string connectionString =
@"Data Source =(LocalDB)\MSSQLLocalDB; AttachDbFilename=|DataDirectory|\DinoData.mdf;Integrated Security= True;";
//if you want to use SQL Server security, set Integrated Security to FALSE. TRUE means use Windows Integrated Security.
string queryString =
"INSERT INTO [DinoTable] VALUES(@name, @height, @heightscale, @weight, @weightscale, @diet, @status, @locationDis, @dayDis, @monthDis, @yearDis, @yourlocation, @dayborn, @monthborn, @yearborn, @Gender, @yourEmail, @yoname, @lastname, @MoneyinMilions);";
//normally, you'd print an error on the form to tell the user why their data was wrong.
if (Session["yourLocation"] != null)
Session["yourlocation"] = ddlcountry.SelectedItem.Text;
else
{
return;
}
if (Session["dayborn"] != null)
Session["dayborn"] = ddlBorn.SelectedItem.Text;
else
{
return;
}
if (Session["monthborn"] != null)
Session["monthborn"] = ddlmonthborn.SelectedItem.Text;
else
{
return;
}
if (Session["yearborn"] != null)
Session["yearborn"] = txtyar.Text;
else
{
return;
}
if (Session["yourEmail"] != null)
Session["yourEmail"] = txtemail.Text;
else
{
return;
}
if (Session["Gender"] != null)
Session["Gender"] = rbGender.SelectedItem.Text;
else
{
return;
}
if (Session["YourName"] != null)
Session["YourName"] = txtName.Text;
else
{
return;
}
if (Session["YourLastName"] != null)
Session["YourLastName"] = txtLName.Text;
else
{
return;
}
if (Page.IsValid == true)
{
using (SqlConnection c = new SqlConnection(connectionString))
{
//not sure why you are just using session objects. If you've disabled session for the controls,
//then it makes sense. Otherwise just use the dropdown's text value directly.
using (SqlCommand newUser = new SqlCommand(queryString, c))
{
newUser.Parameters.AddWithValue("@name", (string)Session["Name"]);
newUser.Parameters.AddWithValue("@height", Convert.ToDouble(Session["Height"]));
newUser.Parameters.AddWithValue("@heightscale", (string)Session["HeightScale"]);
newUser.Parameters.AddWithValue("@weight", Convert.ToDouble(Session["Weight"]));
newUser.Parameters.AddWithValue("@weightscale", (string)Session["weightscale"]);
newUser.Parameters.AddWithValue("@diet", (string)Session["diet"]);
newUser.Parameters.AddWithValue("@status", (string)Session["status"]);
newUser.Parameters.AddWithValue("@locationDis", (string)Session["locationDis"]);
newUser.Parameters.AddWithValue("@dayDis", Convert.ToInt32(Session["dayDis"]));
newUser.Parameters.AddWithValue("@monthDis", (string)(Session["monthDis"]));
newUser.Parameters.AddWithValue("@yearDis", Convert.ToInt32(Session["yearDis"]));
newUser.Parameters.AddWithValue("@yourlocation", (string)Session["yourlocation"]);
newUser.Parameters.AddWithValue("@dayborn", Convert.ToInt32(Session["dayborn"]));
newUser.Parameters.AddWithValue("@monthborn", (string)(Session["monthborn"]));
newUser.Parameters.AddWithValue("@yearborn", Convert.ToInt32(Session["yearborn"]));
newUser.Parameters.AddWithValue("@Gender", (string)Session["Gender"]);
newUser.Parameters.AddWithValue("@yourEmail", (string)Session["yourEmail"]);
newUser.Parameters.AddWithValue("@yoname", (string)Session["YourName"]);
newUser.Parameters.AddWithValue("@lastname", (string)Session["YourLastName"]);
newUser.Parameters.AddWithValue("@MoneyinMilions", 3);
c.Open();
newUser.ExecuteNonQuery(); //if you are not returning a result set, this is what you use. Use ExecuteQuery() if you want to return data from the DB.
c.Close();
}
}
Response.Redirect("finish%20new.aspx", true);
}
}
这是学习如何使用SQL连接的资源。
http://www.codeproject.com/Articles/823854/How-to-connect-SQL-Database-to-your-Csharp-program
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