SQL Server C# 无法插入数据库

Posted 2023-04-12

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【中文标题】SQL Server C# 无法插入数据库【英文标题】：SQL Server C# can't insert in to the database 【发布时间】：2016-05-10 19:35:07 【问题描述】：

问题：

“System.Data.SqlClient.SqlException”类型的异常发生在 System.Data.dll 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 需要参数@monthDis，但未提供该参数

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);

感谢大家的帮助！

【问题讨论】：

您应该查看Can we stop using AddWithValue() already? 并停止使用.AddWithValue() - 它可能会导致意想不到和令人惊讶的结果... 在查询中找不到参数@MoneyinMilions！你能显示表 [DinoTable] 的架构吗？同样不要在INSERT语句中省略列名；我们不知道[DinoTable] 包含什么或它的列的顺序。我不能长时间发表评论 【参考方案1】：

您的 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);

【讨论】：

【参考方案2】：

我很确定您的问题是您的查询。

 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);

您正在将参数添加到查询中，但它很可能为空。 NewUser.Parameters.AddWithValue("@monthDis", (string)(Session["monthDis"]));

您需要检查会话变量是否为空，然后再按照@DevTony 的建议进行传递。

 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);

这是一个学习如何使用 SQL 连接的资源。

http://www.codeproject.com/Articles/823854/How-to-connect-SQL-Database-to-your-Csharp-program

【讨论】：

我不得不去采石场赚到百万美元我对此很陌生，所以你能解释一下我之前应该做什么，为什么？？我强烈建议您尝试在添加了所有参数的 SSMS（Sql Server Management Studio）中运行查询，然后朝着 VS 前进。我还建议您使用存储过程 - 这样，如果您在不同的地方重用此查询，如果问题是缺少参数或其他问题，您可以缩小范围。我将编辑我的答案，以便您可以看到应该做什么以及资源，以便您了解有关这些内容的更多信息。他们不在同一个页面，所以它不会以这种方式工作不过我还是会试试的【参考方案3】：

未分配的会话变量在查询时返回为null。当通过AddWithValue 作为参数传递时，它会产生您所看到的错误。

如果不需要数据库中的值（它是一个可为空的列），那么您可以使用 C# 合并运算符测试 null 并替换为 DBNull.Value：

NewUser.Parameters.AddWithValue("@monthDis", Session["monthDis"] ?? DBNull.Value);

或者，如果需要该值（NOT NULL 列），那么您应该提供一个默认值（或抛出异常）：

NewUser.Parameters.AddWithValue("@monthDis", Session["monthDis"] ?? "");

我对构建 SQL 参数的代码部分进行了微调（包括在 Name 是 null 时抛出异常，因为那是主键）：

//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，在插入时，必须将所有未在数据库中配置默认值的表的必填字段指定为查询字符串中的参数。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);";

【讨论】：

感谢您发布表格结构。我没有意识到这些字段是不可为空的。为了完整起见，我已经修正了我的答案，并包含了 bjones 和 Richard_D 的建议，希望其中有一些有用的部分。

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