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The data i inserted does not show in the DataBase

I have an form that looks like that.Whenever I insert the Name and Age into the database and i press Show,it shows me all the entries(including the ones I just entered) but in the dbo.Table it does not update,everytime I try to refresh it gives me an error like this
I created the data base using Add->New Item->Service Base DataBase
This is the code for Inserting data:
private void button1_Click(object sender, EventArgs e)
{
string sql = "Insert into Elevi(Name,Age) values(#Name,#Age)";
command = new SqlCommand(sql, myConnection);
try
{
command.Parameters.AddWithValue("#Name", textBox1.Text);
command.Parameters.AddWithValue("#Age", Convert.ToInt32(textBox2.Text));
command.ExecuteNonQuery();
}
catch(Exception a)
{
MessageBox.Show(a.Message);
}
}
This is the code for Showing the data:
private void button2_Click(object sender, EventArgs e)
{
string sql;
try
{
sql = "Select * from Elevi";
command = new SqlCommand(sql, myConnection);
dataReader = command.ExecuteReader();
while (dataReader.Read())
{
int IdCitit = Int32.Parse(dataReader.GetValue(0).ToString());
string NumeCitit = dataReader.GetValue(1).ToString();
int VarstaCitita = Int32.Parse(dataReader.GetValue(2).ToString());
MessageBox.Show($"Nume : {NumeCitit} \n Varsa : {VarstaCitita} \n Id: {IdCitit}");
}
}
catch (Exception Exceptie)
{
MessageBox.Show(Exceptie.Message);
}
}
For example, if I have the following input and i Press the button for printing the data it will work just fine
,but after I close the form and check the dbo.Elevi[Data] the new input will not be inserted there
The connection string is : #"Data Source=(LocalDB)\MSSQLLocalDB;AttachDbFilename=|DataDirectory|\TestareDataBase.mdf;Integrated Security=True"
I got it from Project->Add new DataSource

I think you code is not wrong, it seams like it is a database error. Perhaps the database file was created with a newer version of SQL Server Express than the one installed on your machine? Your SQL tools in VS are not compatible with the SQL server. Check the versions of the SQL tools.

Usually it happens when transaction doesn't get committed and it remains in memory, thus if we check the values by using same connection then we find latest one but when we try to verify it from table by using other connection we don't find it unless program commits the transaction.
try this:
private void button1_Click(object sender, EventArgs e)
{
using (SqlConnection connection = new SqlConnection(myConnection))
{
SqlCommand command = connection.CreateCommand();
SqlTransaction transaction = connection.BeginTransaction("MyTransaction");
command.Connection = connection;
command.Transaction = transaction;
try
{
command.CommandText = $"Insert into Elevi(Name,Age) values({textBox1.Text},{textBox2.Text})";
command.ExecuteNonQuery();
transaction.Commit();
}
catch(Exception a)
{
MessageBox.Show(a.Message);
}
}
}

ADO.NET programming says error occured - ExecuteNonQuery requires an open and available connection

Right now, my professor requires me to implement a case study using ADO.NET to save data into SQL Server. I have already created a database and tables in SQL Server and I'm trying to create some forms in Visual Studio by C# ADO.NET. I write according to a YouTube video. But I don't know why I cannot save my data to database successfully.
The result as I write my code like this.
Any help would be appreciated.
namespace casestudy
{
public partial class Form2 : Form
{
SqlConnection vcon2 = new SqlConnection(#"Data Source=SOPHIA-PC\SQLEXPRESS;Initial Catalog=casestudy;Integrated Security=True");
public Form2()
{
InitializeComponent();
}
private void Form2_Load(object sender, EventArgs e)
{
try
{
vcon2.Open();
}
catch (Exception ex)
{
MessageBox.Show("error.occured" + ex.Message);
this.Dispose();
}
}
private void button1_Click(object sender, EventArgs e)
{
string vsql = string.Format("insert into Calluser values ({0}, '{1}', '{2}', {3})", Int32.Parse(txtUserID.Text), txtFName.Text, txtLName.Text, Int32.Parse(txtZoneID.Text));
SqlCommand vCom = new SqlCommand(vsql, vcon2);
try
{
vCom.ExecuteNonQuery();
vCom.Dispose();
MessageBox.Show("The User Information stored.");
txtZoneID.Text = "";
txtLName.Text = "";
txtFName.Text = "";
txtUserID.Text = "";
txtUserID.Focus();
}
catch (Exception ex)
{
MessageBox.Show("error.occured" + ex.Message);
this.Dispose();
}
}
}
}

Can you add a check to see if the connection is actually open and if not reopen it just before you call the ExecuteNonQuery()
if (vcon2.State != ConnectionState.Open)
{
vcon2.Open();
}
vCom.ExecuteNonQuery();

Opening the connection when the application or form opens is probably not the best approach. You want to open the connection right before you execute your sql and close it as soon as possible.
That being said, I recommend removing the code from the Form2_Load event. And do everything in the button1_Click or another method you call from there. Even better would be to have a class or component that does the data access for your application. Also use a using statement as it will ensure resources are disposed even if an exception is thrown.
using (SqlConnection connection = new SqlConnection(#"Data Source=SOPHIA-PC\SQLEXPRESS;Initial Catalog=casestudy;Integrated Security=True");))
{
SqlCommand command = new SqlCommand(vsql, connection);
command.Connection.Open();
command.ExecuteNonQuery();
}
Some info on the using statement:
http://www.dotnetperls.com/using
https://msdn.microsoft.com/en-us/library/yh598w02.aspx

SQL query doesn't get inserted

I've been trying to get my query to work for some time it runs but doesn't insert anything nor does it return any errors.
The database connection is open and is successfuly connection.
The Table is called errorlog and holds the following data
- id (int autoincremental, Primary key, Unique)
- exception (varchar)
- time (DateTime)
exception = String(error message)
time = DateTime.Now
Here's the code:
public void insertError(string error, DateTime time)
{
SqlCeParameter[] sqlParams = new SqlCeParameter[]
{
new SqlCeParameter("#exception", error),
new SqlCeParameter("#time", time)
};
try
{
cmd = new SqlCeCommand();
cmd.Connection = connection;
cmd.CommandType = CommandType.Text;
cmd.CommandText = "INSERT INTO errorlog (exception, time) VALUES(#exception, #time)";
cmd.Parameters.AddRange(sqlParams);
cmd.ExecuteNonQuery();
}
catch (Exception e)
{
Console.WriteLine(e.Message);
}
}
Any help would be appreciated, Thanks in advance.
EDIT
Removed quotes around #exception
Heres the connection:
protected DataController()
{
try
{
string appPath = System.IO.Path.GetDirectoryName(Assembly.GetAssembly(typeof(DataController)).CodeBase).Replace(#"file:\", "") + #"\";
string strCon = #"Data Source = " + appPath + #"Data\EasyShop.sdf";
connection = new SqlCeConnection(strCon);
}
catch (Exception e)
{
}
connection.Open();
}
Finally the way it gets called:
public bool log(string msg, bool timestamp = true)
{
DataController dc = DataController.Instance();
dc.insertError(msg, DateTime.Today);
return true;
}

Debug your application and see if connection points exactly to the
database you want. Also check if you look for the inserted records
in the same database.
If your connection belongs to the transaction, check if it's committed. You will not see those records inserted until transaction is committed.
It seems to me, that you INSERT is wrong. Remove quotes around #exception
Open SQL Server Profiler, connect to your database and check if your INSERT appears in there.

Why are there connections open to my databases?

I have a program that stores user projects as databases. Naturally, the program should allow the user to create and delete the databases as they need to. When the program boots up, it looks for all the databases in a specific SQLServer instance that have the structure the program is expecting. These database are then loaded into a listbox so the user can pick one to open as a project to work on.
When I try to delete a database from the program, I always get an SQL error saying that the database is currently open and the operation fails. I've determined that the code that checks for the databases to load is causing the problem. I'm not sure why though, because I'm quite sure that all the connections are being properly closed.
Here are all the relevant functions. After calling BuildProjectList, running "DROP DATABASE database_name" from ExecuteSQL fails with the message: "Cannot drop database because it is currently in use". I'm using SQLServer 2005.
private SqlConnection databaseConnection;
private string connectionString;
private ArrayList databases;
public ArrayList BuildProjectList()
{
//databases is an ArrayList of all the databases in an instance
if (databases.Count <= 0)
{
return null;
}
ArrayList databaseNames = new ArrayList();
for (int i = 0; i < databases.Count; i++)
{
string db = databases[i].ToString();
connectionString = "Server=localhost\\SQLExpress;Trusted_Connection=True;Database=" + db + ";";
//Check if the database has the table required for the project
string sql = "select * from TableExpectedToExist";
if (ExecuteSQL(sql)) {
databaseNames.Add(db);
}
}
return databaseNames;
}
private bool ExecuteSQL(string sql)
{
bool success = false;
openConnection();
SqlCommand cmd = new SqlCommand(sql, databaseConnection);
try
{
cmd.ExecuteNonQuery();
success = true;
}
catch (SqlException ae)
{
MessageBox.Show(ae.Message.ToString());
}
closeConnection();
return success;
}
public void openConnection()
{
databaseConnection = new SqlConnection(connectionString);
try
{
databaseConnection.Open();
}
catch(Exception e)
{
MessageBox.Show(e.ToString(), "Error",
MessageBoxButtons.OK, MessageBoxIcon.Error);
}
}
public void closeConnection()
{
if (databaseConnection != null)
{
try
{
databaseConnection.Close();
}
catch (Exception e)
{
MessageBox.Show(e.ToString(), "Error",
MessageBoxButtons.OK, MessageBoxIcon.Error);
}
}
}

The SqlConnection class polls the actual database connection. If you close the SqlConnection, the connection is returned to the Connection pool. To prevent this behaviour, set SqlConnection.Pooling = false;.
edit
John seems to be more to the point here. But you might have to keep polling in mind as well.

Two comments. First off, you should use a using statement and your could will be much cleaner.
More on topic, you are connecting to the database when you are trying to drop it! Connect to the master database instead.

How do I connect to a SQL database from C#?

I am trying to write a local program management and install system for my home network, and I think I've got the technologies nailed down:
C#/.NET/WPF for the client
Lua for installation scripting support (through LuaInterface)
SQL Server Express for maintaining a database of programs
However I'm unsure what specifically I'll use to connect C# to the database. Is there something built into the .NET framework for this? Bonus points if you have a suggestion on what I should use for interacting with said database.

Check out
Introduction to ADO.NET Tutorial
ADO.NET Tutorial Lesson 1
An introduction to ADO.NET
I'm sure there's plenty more out there - just google for "ADO.NET" and "Tutorial" ......
UPDATE:
If you want to connect to your local SQL Server Express, and connect to the "Northwind" database, and read the top 5 customers from the "Customers" table, you'd have to do something like this:
string connectionString = "server=(local)\SQLExpress;database=Northwind;integrated Security=SSPI;";
using(SqlConnection _con = new SqlConnection(connectionString))
{
string queryStatement = "SELECT TOP 5 * FROM dbo.Customers ORDER BY CustomerID";
using(SqlCommand _cmd = new SqlCommand(queryStatement, _con))
{
DataTable customerTable = new DataTable("Top5Customers");
SqlDataAdapter _dap = new SqlDataAdapter(_cmd);
_con.Open();
_dap.Fill(customerTable);
_con.Close();
}
}
Now you would have all 5 top customers from your Northwind database in the DataTable and you can inspect them, print them out, manipulate them - whatever you want to do.
That's ADO.NET in action!
As for the details of the connection string - what options you can use and what it should look like, check out the Connection Strings web site - it has tons of examples and explanations.
Marc

SqlConnection
object is made for this.
Eg:
SqlConnection conn = new SqlConnection(
"Data Source=(local);Initial Catalog=Northwind;Integrated Security=SSPI");
or
SqlConnection conn = new SqlConnection(
"Data Source=DatabaseServer; Initial Catalog=Northwind; User ID=YourUserID; Password=YourPassword");
conn.Open(); // opens the database connection
Edit:
After doing all your stuff you have to close the connection by
conn.Close();
Data Source: Identifies the server. Could be local machine, machine domain name, or IP Address.
Initial Catalog: Database name.
Integrated Security: Set to SSPI to make connection with user's Windows login
User ID: Name of user configured in SQL Server.
Password: Password matching SQL Server User ID.

To connect to SQL Server Express you need nothing but System.Data, which is a standard .NET assembly. Just use SqlXXX classes and you'll be done.
However, writing mundane ADO.NET code is very boring, so it's very common to use an ORM or less heavy-weight result-set mapper such as BLToolkit.
And finally, consider using SQL Server CE. This is a fully ACID-compliant single-file embedded database engine which supports pretty much any feature you can expect form an SQL RDBMS.

You can use ADO.Net and System.Data.SqlClient namespace for the same. I will advise you to go with Entities framework (ORM). Please find below links for Entity Framework walk through
http://thedatafarm.com/LearnEntityFramework/tutorials/creating-an-ado-net-entity-framework-entity-data-model/
http://thedatafarm.com/LearnEntityFramework/tutorials/use-an-entity-framework-entity-as-a-winforms-data-source/

I would recommend using Microsoft's Patterns & Practices Enterprise Library. You would specifically be using the The Data Access Application Block.
An excerpt from MSDN:
The Data Access Application Block
provides the following benefits:
It uses the functionality provided by ADO.NET 2.0 and with it, you can
use ADO.NET functionality along with
the application block's functionality.
It reduces the need to write boilerplate code to perform standard
tasks.
It helps maintain consistent data access practices, both within an
application and across the enterprise.
It reduces difficulties in changing the database type.
It relieves developers from learning different programming models
for different types of databases.
It reduces the amount of code that developers must write when they port
applications to different types of
databases.
I've used this method for years and it's been very successfull thus far. Good luck!

I wish this will help
just try these..
#CLASS
using System.Data;
using System.Data.SqlClient;
namespace WindowsFormsApplication2
{
class clsDB
{
public SqlDataAdapter mDataAdapter = new SqlDataAdapter();
public DataSet mDataSet = new DataSet();
public SqlConnection mConn;
public clsDB()
{
mConn = new SqlConnection("Data Source=(the data source);Initial Catalog=sample;User ID=(the id);Password=(the password)");
}
public void SQLDB(string strSQL)
{
try
{
mDataAdapter = new SqlDataAdapter(new SqlCommand(strSQL, mConn));
mDataSet = new DataSet();
mDataAdapter.Fill(mDataSet);
}
catch (Exception ex)
{
throw ex;
}
finally
{
mConn.Close();
}
}
public void ClearRes()
{
mDataAdapter.Dispose();
mDataAdapter = null;
mDataSet.Dispose();
if (mConn.State != ConnectionState.Closed)
{
mConn.Close();
}
}
}
}
#LOGIN
public partial class Login : Form
{
clsDB x = new clsDB();
public Login()
{
InitializeComponent();
}
private void btnSubmit_Click(object sender, EventArgs e)
{
x.SQLDB("select * from tbl_accounts where u_username ='" + txtUser.Text + "' and u_password ='" + txtPass.Text + "'");
if (x.mDataSet.Tables[0].Rows.Count > 0)
{
Main a = new Main();
this.Hide();
a.Show();
}
else
{
MessageBox.Show("wrong username or password");
}
}
#MAIN ACCESS
namespace WindowsFormsApplication2
{
public partial class Main : Form
{
clsDB x = new clsDB();
public Main()
{
InitializeComponent();
}
private void btnAdd_Click(object sender, EventArgs e)
{
x.SQLDB("insert into tbl_info (u_lastname, u_firstname, u_middlename) values ('" + atxtLN.Text + "','" + atxtFN.Text + "','" + atxtFN.Text + "')");
fillgrid();
}
private void Main_Load(object sender, EventArgs e)
{
x.SQLDB(" select * from tbl_info ");
dgv1.DataSource = x.mDataSet.Tables[0];
fillgrid();
}
void fillgrid()
{
x.SQLDB("select * from tbl_info");
dgv1.DataSource = null;
dgv1.DataSource = x.mDataSet.Tables[0];
}
void search()
{
x.SQLDB("SELECT * from tbl_info where u_id like '" + etxtID.Text + "%' order by u_id");
if (x.mDataSet.Tables[0].Rows.Count > 0)
{
x.mDataAdapter.Fill(x.mDataSet, "tbl_info");
dgv1.DataSource = x.mDataSet.Tables["tbl_info"].DefaultView;
etxtLN.Text = dgv1.Rows[dgv1.CurrentRow.Index].Cells["u_lastname"].Value.ToString();
etxtFN.Text = dgv1.Rows[dgv1.CurrentRow.Index].Cells["u_firstname"].Value.ToString();
etxtMN.Text = dgv1.Rows[dgv1.CurrentRow.Index].Cells["u_middlename"].Value.ToString();
}
else if (etxtID.Text == "Type User ID to Edit")
{
etxtLN.Text = "";
etxtFN.Text = "";
etxtMN.Text = "";
}
else
{
etxtLN.Text = "";
etxtFN.Text = "";
etxtMN.Text = "";
}
}
private void etxtID_TextChanged(object sender, EventArgs e)
{
}
private void etxtID_Enter(object sender, EventArgs e)
{
etxtID.Text = "";
etxtID.ForeColor = Color.Black;
}
private void etxtID_Leave(object sender, EventArgs e)
{
if (etxtID.Text == "")
{
etxtID.ForeColor = Color.Gray;
etxtID.Text = "Type User ID to Edit";
x.SQLDB(" select * from tbl_info ");
dgv1.DataSource = x.mDataSet.Tables[0];
fillgrid();
}
}
private void etxtID_KeyUp(object sender, KeyEventArgs e)
{
search();
}
private void btnUpdate_Click(object sender, EventArgs e)
{
x.SQLDB("UPDATE tbl_info set u_lastname ='" + etxtLN.Text + "', u_firstname ='" + etxtFN.Text + "', u_middlename ='" + etxtMN.Text + "' where u_id =" + etxtID.Text);
MessageBox.Show("Operation Successful!");
fillgrid();
}
private void btnDelete_Click(object sender, EventArgs e)
{
x.SQLDB("delete from tbl_info where u_id =" + dtxtID.Text + "");
MessageBox.Show("Operation Successful!");
fillgrid();
}
}
}

Currently the easiest way to connect to your database and perform queries in C# is LinqToSQL. It will save you a lot of headache as compared to using "old-school" ADO connections.

Sure of course, you can just use the classes in System.Data.SqlClient, though most people will use an ORM. I use LLBLGen Pro.

You can use https://github.com/MohamadParsa/AdoDbConnection.Net and use the project as a project reference in your solution and enjoy. Also, you can explore DBConnection.cs file and copy class or method in your project.
but ... for make a connection or disconnect to express you can use:
SqlConnection con = new SqlConnection();
SqlCommand cmd = new SqlCommand();
SqlDataAdapter da = new SqlDataAdapter();
string _ErorrString = "";
string _InternalErorrString = "";
private void Connect()
{
cmd.Connection = con;
da.SelectCommand = cmd;
try
{
string cs = "";
cs = #"Data source=.\SQLEXPRESS;Attachdbfilename=|DataDirectory|\"
+ DataBbaseName + ".mdf;Integrated security=true;user Instance=true";
con.ConnectionString = cs;
con.Open();
}
catch (Exception ex)
{
_ErorrString += "Erorr NO. : 100" + ", connection error.";
_InternalErorrString += ex.Message;
}
}
private void Disconnect()
{
con.Close();
}
and to execution command and get results:
public DataSet RunAndGet(string sql)
{
//first, make a connection
Connect();
//to hold and return results
DataSet dataSet = new DataSet();
try
{
//set command
cmd.CommandText = sql;
//run and fill results into the dataset
da.Fill(dataSet);
}
catch (Exception ex)
{
_ErorrString += "Erorr NO. : 101" + ", internal error.";
_InternalErorrString += ex.Message;
}
//finally closes connection
Disconnect();
return dataSet;
}