Develop Reference

Basic inserting data into SQL Server database

I'm a newbie in Visual Studio and I want to make a database system that allows the user to insert, update, delete and search data using a Windows Forms application.
I already watched 3 tutorial how but I'm getting the same error. when I delete my ExecuteNonQuery() call, it doesn't have any error but the data I entered into my textboxes is not inserted into my database. When I put it back I'm getting this kind of error
ERROR:
CODE:
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Data.SqlClient;
using System.Threading.Tasks;
namespace EaglePlannersDatabase
{
public partial class Form1 : Form
{
SqlConnection connection = new SqlConnection(#"Data Source=(LocalDB)\MSSQLLocalDB;AttachDbFilename=C:\Users\Adrian\Documents\EaglePlannersDataBase.mdf;Integrated Security=True;Connect Timeout=30");
public Form1()
{
InitializeComponent();
}
private void InsertButton_Click(object sender, EventArgs e)
{
connection.Open();
SqlCommand cmd = new SqlCommand("Insert Into EAGLEPLANNERS(policy number,plan type,renewal date,name,age,address,birthday,email,home/office number,mode of payment,amount) values (#policy number,#plan type,#renewal date,#name,#age,#address,#birthday,#email,#home/office number,#mode of payment,#amount)", connection);
cmd.Parameters.AddWithValue("#policy number", int.Parse(policyNumbertxtbox.Text));
cmd.Parameters.AddWithValue("#plan type", planTypetxtbox.Text);
cmd.Parameters.AddWithValue("#renewal date", int.Parse(renewalDatetxtbox.Text));
cmd.Parameters.AddWithValue("#name", nametxtbox.Text);
cmd.Parameters.AddWithValue("#age", int.Parse(agetxtbox.Text));
cmd.Parameters.AddWithValue("#address", addresstxtbox.Text);
cmd.Parameters.AddWithValue("#birthday", int.Parse(birthdaytxtbox.Text));
cmd.Parameters.AddWithValue("#email", (emailtxtbox.Text));
cmd.Parameters.AddWithValue("#home/office number", int.Parse(homeofficetxtbox.Text));
cmd.Parameters.AddWithValue("#mode of payment", (modeofpaymenttxtbox.Text));
cmd.Parameters.AddWithValue("#amount", int.Parse(amounttxtbox.Text));
cmd.ExecuteNonQuery();
connection.Close();
policyNumbertxtbox.Text = "";
planTypetxtbox.Text = "";
renewalDatetxtbox.Text = "";
nametxtbox.Text = "";
agetxtbox.Text = "";
addresstxtbox.Text = "";
birthdaytxtbox.Text = "";
emailtxtbox.Text = "";
homeofficetxtbox.Text = "";
modeofpaymenttxtbox.Text = "";
amounttxtbox.Text = "";
MessageBox.Show("Record inserted successfully!");
}
}
}

As a newbie, getting the pieces working first, then applying to the user interface I would apply second. I will try to summarize each piece. First your connection itself looked strange as others have pointed out. I would try to first make sure the connection itself works before applying any attempt at sql insert/update/delete going on. So you might try
SqlConnection connection = new SqlConnection(
#"Data Source (LocalDB)\MSSQLLocalDB; AttachDbFilename=C:\Users\Adrian\Documents\EaglePlannersDataBase.mdf;
Integrated Security=True;
Connect Timeout=30" );
private void TestConnect()
{
if( connection.Open() )
// great, you have a good connection
connection.Close();
else
// message to yourself why a failed connection and fix it...
}
Once you know your connection is good, then on to your sql-insert. Having good column names is important. Dont try to be fancy with human readable with spaces types of column names, just causes headaches. Use simple and direct as others have pointed out in prior comments. Also, when parameterizing, I have tried to always slightly alter the insert/update/delete parameters with a "p" prefix indicating the PARAMETER FOR the column, such as
insert into SomeTable ( oneColumn, secondCol ) values ( #pOneColumn, #pSecondCol )
just to avoid bad confusion. If an error comes out via "oneColumn" vs "pOneColumn" in the message, you KNOW which thing is at fault. The column itself does not work, or the specific parameter/value being supplied.
Next, readability of your SQL statements, especially as they get longer. Use spaces and I typically use a leading "#" before the quoted sql command to allow for line continuations as I edited your previous answer. So the same above insert would be written more like
var cmd = new SqlCommand(
#"insert into SomeTable
( oneColumn,
secondCol
)
values
( #pOneColumn,
#pSecondCol
)", connection );
So if you ever needed to add additional columns (or remove), you can see the paired set of insert columns vs parameters much easier.
Now the testing. Don't try to work off some user-entered values, put in known VALID values so you dont have to worry about user entered values. Get the command to WORK, then pull values from interface later. (continuing from above sample)
cmd.Parameters.AddWithValue("#pOneColumn", 17 );
cmd.Parameters.AddWithValue("#pSecondCol", "some Text");
Then try to execute that and make sure IT works. Once it does, THEN start pulling from your user interface
cmd.Parameters.AddWithValue("#pOneColumn", int.Parse( yourTextControl.Text ));
cmd.Parameters.AddWithValue("#pSecondCol", anotherTextControl.Text );
Find your mistakes BEFORE you let any human interaction get into and screw-up the rest of what you think SHOULD work.
Note, if you make public properties to your view models such as
public int someAge {get; set;}
and then set the bindings of the data entry control in the screen to this someAge property, it will only allow a numeric entry to be entered and will otherwise have a value of zero if someone tries to put in text. Similarly if you are dealing with dates, and if date/time, always use datetime fields for querying purposes vs formatted date as a text field. You will thank yourself in the future when querying for things within date range periods. HTH
Finally,try to avoid using AddWithValue. Instead, properly identify the expected data type as described in the linked article. I just left original context to your code for testing and debug researching purposes.

This would be the possible answer on your question, what I have done here, first I changed your connection string by removing AttachDbFilename attribute, and replace that by adding of Initial Catalog attribute where I set the name of your database.
Next thing, I declared variables where the values from textboxes will be stored, these values of variables will be our parameters, this is not necessary to do, it is just my own style, you can keep as you done.
I have seen also, that you are not using try/catch/finally block and you are closing the connection in the same part of code where you opening the connection, and maybe that is the reason why your values are not being stored into the table, so I decided to round your code within that block. If you don't know what is try/catch/finally block you can read the documentation here . We are opening the connection and do all operations on database in try block, in catch block we are catching all errors that might be caused in our application and in finally we are closing the connection. You will also notice that I created additional check, where I checking the result of ExecuteNonQuery() method, and if result of ExecuteNonQuery method is equals to 1 - records is inserted successfully, otherwise it fails.
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Data.SqlClient;
using System.Threading.Tasks;
namespace EaglePlannersDatabase
{
public partial class Form1 : Form
{
SqlConnection connection = new SqlConnection(#"Data Source=(LocalDB)\MSSQLLocalDB;Initial Catalog=EaglePlannersDataBase;Integrated Security=True;Connect Timeout=30");
public Form1()
{
InitializeComponent();
}
private void label1_Click(object sender, EventArgs e)
{
}
private void InsertButton_Click(object sender, EventArgs e)
{
int policyNumber = Convert.ToInt32(policyNumbertxtbox.Text);
string planType = planTypetxtbox.Text;
int renewalDate = Convert.ToInt32(renewalDatetxtbox.Text);
string name = nametxtbox.Text;
int age = Convert.ToInt32(agetxtbox.Text);
string address = addresstxtbox.Text;
int birthday = Convert.ToInt32(birthdaytxtbox.Text);
string email = emailtxtbox.Text;
int homeOfficeNumber = Convert.ToInt32(homeofficetxtbox.Text);
string modeOfPayment = modeofpaymenttxtbox.Text;
int amount = Convert.ToInt32(amounttxtbox.Text);
try
{
connection.Open();
SqlCommand cmd = new SqlCommand("Insert Into tbl1 (PolicyNumber,planType,renewalDate,name,age,address,birthday,email,homeOfficeNumber,modeOfPayment,amount) values (#PolicyNumber,#planType,#renewalDate,#name,#age,#address,#birthday,#email,#homeOfficeNumber,#modeOfPayment,#amount)", connection);
cmd.Parameters.AddWithValue("#PolicyNumber",policyNumber);
cmd.Parameters.AddWithValue("#planType",planType);
cmd.Parameters.AddWithValue("#renewalDate",renewalDate);
cmd.Parameters.AddWithValue("#name",name);
cmd.Parameters.AddWithValue("#age",age);
cmd.Parameters.AddWithValue("#address",address);
cmd.Parameters.AddWithValue("#birthday",birthday);
cmd.Parameters.AddWithValue("#email",email);
cmd.Parameters.AddWithValue("#homeOfficeNumber",homeOfficeNumber);
cmd.Parameters.AddWithValue("#modeOfPayment",modeOfPayment);
cmd.Parameters.AddWithValue("#amount",amount);
int result = cmd.ExecuteNonQuery();
if(result == 1)
{
MessageBox.Show("Record Inserted Successfully!");
policyNumbertxtbox.Text = "";
planTypetxtbox.Text = "";
renewalDatetxtbox.Text = "";
nametxtbox.Text = "";
agetxtbox.Text = "";
addresstxtbox.Text = "";
birthdaytxtbox.Text = "";
emailtxtbox.Text = "";
homeofficetxtbox.Text = "";
modeofpaymenttxtbox.Text = "";
amounttxtbox.Text = "";
}
else
{
MessageBox.Show("Something went wrong!");
}
}
catch(SqlException ex)
{
MessageBox.Show("We have found error with operation on database: " + ex.Message);
}
catch(Exception ex)
{
MessageBox.Show("We have found error in your code: " + ex.Message);
}
finally
{
connection.Close();
}
}
}
}

here's my new code
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Data.SqlClient;
using System.Threading.Tasks;
namespace EaglePlannersDatabase
{
public partial class Form1 : Form
{
SqlConnection connection = new SqlConnection(#"Data Source=(LocalDB)\MSSQLLocalDB;AttachDbFilename=C:\Users\Adrian\Documents\EaglePlannersDataBase.mdf;Integrated Security=True;Connect Timeout=30");
public Form1()
{
InitializeComponent();
}
private void label1_Click(object sender, EventArgs e)
{
}
private void InsertButton_Click(object sender, EventArgs e)
{
connection.Open();
SqlCommand cmd = new SqlCommand(
#"Insert Into tbl1
( PolicyNumber,
planType,
renewalDate,
name,
age,
address,
birthday,
email,
homeOfficeNumber,
modeOfPayment,
amount )
values
( #PolicyNumber,
#planType,
#renewalDate,
#name,
#age,
#address,
#birthday,
#email,
#homeOfficeNumber,
#modeOfPayment,
#amount )", connection);
cmd.Parameters.AddWithValue("#PolicyNumber", int.Parse(policyNumbertxtbox.Text));
cmd.Parameters.AddWithValue("#planType", planTypetxtbox.Text);
cmd.Parameters.AddWithValue("#renewalDate", int.Parse(renewalDatetxtbox.Text));
cmd.Parameters.AddWithValue("#name", nametxtbox.Text);
cmd.Parameters.AddWithValue("#age", int.Parse(agetxtbox.Text));
cmd.Parameters.AddWithValue("#address", addresstxtbox.Text);
cmd.Parameters.AddWithValue("#birthday", int.Parse(birthdaytxtbox.Text));
cmd.Parameters.AddWithValue("#email", (emailtxtbox.Text));
cmd.Parameters.AddWithValue("#homeOfficeNumber", int.Parse(homeofficetxtbox.Text));
cmd.Parameters.AddWithValue("#modeOfPayment", (modeofpaymenttxtbox.Text));
cmd.Parameters.AddWithValue("#amount", int.Parse(amounttxtbox.Text));
cmd.ExecuteNonQuery();
connection.Close();
policyNumbertxtbox.Text = "";
planTypetxtbox.Text = "";
renewalDatetxtbox.Text = "";
nametxtbox.Text = "";
agetxtbox.Text = "";
addresstxtbox.Text = "";
birthdaytxtbox.Text = "";
emailtxtbox.Text = "";
homeofficetxtbox.Text = "";
modeofpaymenttxtbox.Text = "";
amounttxtbox.Text = "";
MessageBox.Show("Record Inserted Successfully!");
}
}
}
here's my database

Getting Syntax Error When using 'Insert into' command in c#

I get syntax error when using 'Insert into' SQL command using c#. I'm using Access db to store some data.
Surprisingly, when I copy the exact command into MS Access to try if it's not correct, it works like charm. I'm a bit confused! I appreciate any idea or help in this regard. Here is my code:
using (OleDbConnection connection = new OleDbConnection(Global.ConString))
{
using (OleDbCommand command = new OleDbCommand())
{
command.Connection = connection;
command.CommandType = CommandType.Text;
command.CommandText = "INSERT INTO Users(Name,UserName,Password,Customers,Jobs,Invoice,Statement,Reports,Users) values (#name,#UserName,#Password,#Customers,#Jobs,#Invoice,#Statement,#Reports,#Users)";
command.Parameters.AddWithValue("#name",fullName.Text );
command.Parameters.AddWithValue("#UserName", userName.Text);
command.Parameters.AddWithValue("#Password", passWord.Text);
command.Parameters.AddWithValue("#Customers", Customers.Checked);
command.Parameters.AddWithValue("#Jobs", Jobs.Checked);
command.Parameters.AddWithValue("#Invoice", Invoice.Checked);
command.Parameters.AddWithValue("#Statement", Statement.Checked);
command.Parameters.AddWithValue("#Reports", Report.Checked);
command.Parameters.AddWithValue("#Users", userDef.Checked);
try
{
connection.Open();
int recordsAffected = command.ExecuteNonQuery();
if (recordsAffected > 0)
{
foreach (Control item in newRecord.Controls)
{
if (item is TextBox) item.ResetText();
}
timer1.Enabled = true;
}
else
MessageBox.Show("Insert Fail");
}
catch (OleDbException err)
{
MessageBox.Show("Somthing wrong. Error no. is: " + err.ErrorCode + "..." + err.Message);
}
}
}

Most likely your issue is the use of a reserved word as an identifier, specifically 'Password'. Wrap that column name in brackets, i.e. [Password] and you should be good to go.
It's best to avoid reserved words if possible. Generally speaking, you should not be storing unhashed passwords in your database so a column name like 'PasswordHash` is appropriate and avoids this issue.

Cannot connect MS Access to C#

I am trying to create a sign-up for our movie database. I am trying to establish a connection from the MS Access that we made. But whenever I run my code, I get an error. I am using Visual Studio Express 2012 C#.
Why does my code trigger this error?
"An unhandled exception of type 'System.Data.OleDb.OleDbException'
occurred in System.Data.dll Additional information: Syntax error in
INSERT INTO statement."
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Data.OleDb;
namespace BigScreen
{
public partial class sign_up : Form
{
private OleDbConnection connection = new OleDbConnection();
public sign_up()
{
InitializeComponent();
}
private void sign_up_Load(object sender, EventArgs e)
{
connection.ConnectionString = #"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\Users\raizel\Desktop\DataBase\Movie_Database.accdb;
Persist Security Info=False;";
}
private void sign_up_FormClosed(object sender, FormClosedEventArgs e)
{
Form1 thisform = new Form1();
thisform.Show();
}
}
private void button1_Click(object sender, EventArgs e)
{
connection.Open();
OleDbCommand command = new OleDbCommand();
command.Connection = connection;
command.CommandText = "Insert into User ([firstname], [lastname], [username], [password]) values ('" + textBox2.Text + "','" + textBox5.Text + "','" + textBox4.Text + "','" + textBox1.Text + "')";
command.ExecuteNonQuery();
userID++;
MessageBox.Show("Data Saved!");
connection.Close();
}
}
}

User is a reserved word. Bracket it like this to inform the db engine that word is an object name:
Insert into [User] ...
You would be wise to switch to a parameterized query as Bradley hinted but you still need to bracket the reserved word there, too.

User is a reserved word at leat in sql server. You have here in your code some things, you are using concatenation and this is making your code in danger of sql injection, the password can be in clear text in the database you need encryption.
You need to use using in your code to be sure the connection is closed after the insert is complete. If the error throw an exception the connection remain open and you will have problem in future attempts to execute anything. Close your db and make sure you can do an action using the designer and then check your code again.
Try to move to sql server ms access is not a good database for your system.
I made this example using your structure in sql fiddle

c# program inserting rows in sql database

I know I have done this a few times before but for the life of me can't remember how.
I have a database I have created and I want to make a software that only inputs information into the database. The program works but my sql connection is the problem. So to test it out I basically tried to do it direct inserting hard-coded info but it still will not go. where am I going wrong?:
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Data.Common;
using System.Data.SqlClient;
using System.Data.Sql;
namespace InventoryTracker
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
public static void CreateCommand()
{
SqlConnection myConnection = new SqlConnection("User Id=Jab" + "password=''" + "Data Source=localhost;" + "Trusted_Connection=yes;" + "database=InventoryTracker;" + "Table=Inventory;");
try
{
myConnection.Open();
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
SqlCommand myCommand = new SqlCommand("INSERT INTO Inventory (ItemName, SerialNumber, Model, Department, Quantity, Notes) " + "Values (string,string,string,string, 1, string)", myConnection);
}
}
}
Thank you in advance! :-)

Your sql connection string is messed up, you need semi-colons between all parameters and your parameters are messed up too. I.e., something like
"Server=localhost;Database=InventoryTracker;Trusted_Connection=True;"
You are mixing trusted mode and specifying the user id -- trusted connection means to use your windows login credentials.
TableName does not go in the connection string.
This site is great for connection string examples http://www.connectionstrings.com/sql-server-2008
You SQL command, "INSERT INTO Inventory (ItemName ..." is pretty messed up too. Should be something like
INSERT INTO Inventory (ItemName ...) values(#ItemName ...)
You then pass in the values like
myCommand.Parameters.Add("ItemName", SqlType.VarChar).Value = "Dozen Eggs";
See Insert data into SQL Server from C# code for a simple example

Just use the SqlConnectionStringBuilder class.
http://msdn.microsoft.com/en-us/library/system.data.sqlclient.sqlconnectionstringbuilder.aspx
Instead of:
"User Id=Jab" + "password=''" + "Data Source=localhost;" + "Trusted_Connection=yes;" + "database=InventoryTracker;" + "Table=Inventory;");
Try:
SqlConnectionStringBuilder builder = new SqlConnectionStringBuilder();
builder.UserID = "Jab";
builder.Password = "";
builder.DataSource = "localhost";
builder.InitialCatalog = "InventoryTracker";

// Don't put table name in your connection string
string connection_str = "Data Source = localhost ; uid = db_user; pwd = db_pass; database = db_name; ";
conn = new SqlConnection(connection_str);
conn.Open();

Try changing
"User Id=Jab" + "password=''" + "Data Source=localhost;" + "Trusted_Connection=yes;" + "database=InventoryTracker;" + "Table=Inventory;"
to
"User Id=Jab; " + "Password=''; " + "Data Source=localhost; " + "Trusted_Connection=yes; " + "Initial Catalog=InventoryTracker;"
(Changed upper/lower case, "Database" to "Initial Catalog", removed "Table" and added ";")
Also, you might want to try replacing "Data Source" by "Server".

Don't forget to call myCommand.ExecuteNonQuery to get it to actually execute your query. Without this, you are just creating a command, but not running it.

Trouble opening SQL connection to insert textbox values

First off, I'd like to say that this is the most brilliant forum I've encountered in my programming journey, and I've been google-fishing for all the help I can get for the last three months. Great support, and even greater style #necromancer badge.
Enough with the flattery.
I'm doing a practice project, insurance website. Right now, I need to get user input from the textboxes into the database. I have seen plenty of related questions here, but I'm getting an error message on my connection I haven't found on any of the other posts, and I'm so ignorant it's difficult to apply examples that don't fit exactly what I'm doing. (As a side note, my trainer specifically wants the most basic form of this code, and as such told me not to worry about parameterizing the queries for security or to use a try-catch block for exceptions, but many thanks to the answers here for those pointers)
The error message I get is "Failed to generate a user instance of SQL Server due to a failure in starting the process for the user instance. The connection will be closed."
Am I getting my syntax wrong? Am I using the 'TextBox1.Text' value right? Am I just too stupid to be doing this?
using System;
using System.Text;
using System.Collections.Generic;
using System.Linq;
using System.Data;
using System.Data.Sql;
using System.Data.SqlClient;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
public partial class SubmissionPage : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
}
protected void Button1_Click(object sender, EventArgs e)
{
String connectionString = #"Data Source=.\SQLEXPRESS;AttachDbFilename=C:\aspnetdb.mdf;Integrated Security=True;User Instance=True";
SqlConnection sqlConn = new SqlConnection(connectionString);
sqlConn.Open();
String thisQuery = "INSERT INTO Customer (" + " Name, SIC_NAIC, Address, City, State, Zip, " + ") VALUES (" + " #TextBox1.Text, #RadioButtonList1.SelecedItem, #TextBox2.Text, #DropDownList1.SelectedItem, #TextBox3.Text" + ")";
SqlCommand thisCommand = new SqlCommand(thisQuery, sqlConn);
thisCommand.ExecuteNonQuery();
sqlConn.Close();
}
}

Check this and use sql parameters:
using (var conn = new SqlConnection("Data Source=.\SQLEXPRESS;Initial Catalog=aspnetdb;Integrated Security=True;Connect Timeout=30;User Instance=True"))
{
conn.Open();
using (var cmd = new SqlCommand("INSERT INTO Customer (Name,SIC_NAIC) VALUES (#Name,#SIC_NAIC)",conn))
{
try
{
cmd.Parameters.Add("#Name", SQlDbType.VarChar, 50).Value = TextBox1.Text;
cmd.Parameters.Add("#SIC_NAIC", SQlDbType.VarChar, 50).Value = RadioButtonList1.SelecedItem.ToString();
cmd.ExecuteNonQuery();
}
catch (Exception)
{
{
}
throw;
}
finally
{
if (conn.State == ConnectionState.Open) conn.Close();
}
}
Make sure you have downloaded sqlmanagement studio 2008 express.. and then attach asp.netdb on it and change your sql connectionstring.
sql ms
Regards

This error is often caused because the parent instance (for whatever reason) can't copy the system databases to the users local isolated storage folders. Sometimes it is because of a previous install of SQL Express has left files in that directory. Full story here
http://social.msdn.microsoft.com/Forums/en/sqldatabaseengine/thread/f5eb164d-9774-4864-ae05-cac99740949b

could be due to permission issue, check eventlog. you may try removing User Instance=True from connection string

In addition to answers regarding SQL database instances, your SQL query looks wrong. Try changing your embedded query to:
String thisQuery = "INSERT INTO Customer (Name, SIC_NAIC, Address, City, State, Zip) VALUES ('" + TextBox1.Text + "', '" + RadioButtonList1.SelecedItem.Text + "', '" + TextBox2.Text + "', '" + DropDownList1.SelectedItem.Text + "', '" + TextBox3.Text + "', '" + TextBoxZip.Text + "')";
This will format the SQL statement from the values on your form.
NOTE: Assuming field SIC_NAIC and State are storing text values and an additional field for Zip (TextBoxZip).

First of all, if your mdf resides at App_Data, then your connection string is all wrong.
Put the following in your web.config
<connectionStrings>
<add name="MyConnectionString" connectionString="Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\aspnetdb.mdf;Integrated Security=True;User Instance=True" providerName="System.Data.SqlClient"/>
</connectionStrings>
Now call it like
string connectionString = System.Configuration.ConfigurationManager.ConnectionStrings["MyConnectionString"].ConnectionString;
Here is a fix for your error. But you should have an instance of SQL Express installed, which I supposecomes standard with Visual Studio.
http://www.aspdotnetfaq.com/Faq/fix-error-Failed-to-generate-a-user-instance-of-SQL-Server-due-to-a-failure-in-starting-the-process-for-the-user-instance.aspx
And while you are at it, please alter your Button_Click event like this
protected void Button1_Click(object sender, EventArgs e)
{
string connectionString = System.Configuration.ConfigurationManager.ConnectionStrings["MyConnectionString"].ConnectionString;
string sql = "INSERT INTO Customer (Name, SIC_NAIC, Address, City, State, Zip) VALUES ('{0}', '{1}', '{2}', '{3}', '{4}', '{5}')";
using (SqlConnection connection = new SqlConnection(connectionString))
{
connection.Open();
string query = String.Format(sql,
TextBox1.Text,
RadioButtonList1.SelectedItem.Text,
TextBox2.Text,
DropDownList1.SelectedItem.Text,
TextBox3.Text,
"000000");
using (SqlCommand command = new SqlCommand(query, connection))
{
command.ExecuteNonQuery();
}
}
}
Also keep in mind that you cannot insert RadioButtonList1.SelecedItem or DropDownList1.SelectedItem to database. You must append either .Text or .Value to it as per your requirement.

Ok guys, first of all I'm overwhelmed by the helpfulness I found here. I'll be a stackoverflow-er for life. Thank you all for taking your time and experience to aid a total stranger. I couldn't have gotten this done without it.
I wanted to post the code I ended up with, just so as to have a record of what actually worked for me in case someone with the same issue needs to see the end result. As per #yetanothercoder's recommendation, I placed this connection string in my webconfig file, and it looked like this (from ?xml version... to configuration is just to show where I placed the code, since I had wondered about that myself, the connection string is wrapped between the tags):
<?xml version="1.0"?>
<!--
For more information on how to configure your ASP.NET application, please visit
http://go.microsoft.com/fwlink/?LinkId=169433
-->
<configuration>
<connectionStrings>
<add name="MyConnectionString" connectionString="Data Source=The-Crushinator\SQLEXPRESS;AttachDbFilename=|DataDirectory|\ArgonautSubmission.mdf;Integrated Security=True;User Instance=True" providerName="System.Data.SqlClient"/>
</connectionStrings>
And, although my trainer assured me that the using block #yetanothercoder suggested should be fine, it wasn't working for me, so I used the example from #chaps' answer, remembering to put in the TextBox4.Text value forgot. The code looks like this:
using System;
using System.Text;
using System.Collections.Generic;
using System.Linq;
using System.Data;
using System.Data.Sql;
using System.Data.SqlClient;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
public partial class SubmissionPage : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
}
protected void Button1_Click(object sender, EventArgs e)
{
string connectionString = System.Configuration.ConfigurationManager.ConnectionStrings["MyConnectionString"].ConnectionString;
String thisQuery = "INSERT INTO Customer (Name, SIC_NAIC, Address, City, State, Zip) VALUES ('" + TextBox1.Text + "', '" + RadioButtonList1.SelectedItem.Text + "', '" + TextBox2.Text + "', '" + TextBox3.Text + "', '" + DropDownList1.SelectedItem.Text + "', '" + TextBox4.Text + "')";
using (SqlConnection sqlConn = new SqlConnection(connectionString))
{
sqlConn.Open();
using (SqlCommand command = new SqlCommand(thisQuery, sqlConn))
{
command.ExecuteNonQuery();
}
}
}
}
Next came the more convoluted part. To rid myself of the dreaded "Failed to generate a user instance of SQL Server due to a failure in starting the process for the user instance. The connection will be closed" error message, I followed this link from #yetanother coder,
and found that I needed to install Sql Server Management Studio Express. I had to use Microsoft Web Platform Installer because when I tried to follow the instructions at msdn.com for downloading ssmse, I kept getting a cyclical error. I installed ssmse, opened up the query window with the 'new query' button, and executed this command
exec sp_configure 'user instances enabled', 1.
Go
Reconfigure
then I restarted sql server, added a new database to my asp.net project, and BAM! It worked! User info was saved into the database, where it was supposed to go! I had been so conditioned to expecting failure from my code that it felt like watching my first rocket make it into orbit. Awesome. Thanks again, everyone, and I hope this helps someone in a similar situation.