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Database update error with SQL Server 2012 and C#

I am trying to update my data in a SQL Server database through C#. I am getting updated. But the problem is the data is updated twice.
For example I have 10 (int) in my balance and if I add another 10, it turns to 30.
Any help would be appreciated.
Here is my code:
protected void LoginClick(object sender, EventArgs e)
{
DataTable dr = new DataTable();
string email = txtEmail.Text;
SqlConnection con = new SqlConnection(Ws.Con);
con.Open();
int s = Convert.ToInt32(add.Text);
SqlCommand cmd = new SqlCommand("Update [Order] set Balance=Balance+'" + s + "',Card='" + card.Text + "' where email=#email ", con);
cmd.Parameters.AddWithValue("email", email);
SqlDataAdapter sda = new SqlDataAdapter(cmd);
DataTable dt = new DataTable();
sda.Fill(dt);
int i = cmd.ExecuteNonQuery();
con.Close();
}

I would like to rectify few mistakes in your code,
DataTable is not needed to execute the update query, ExecuteNonQuery will do the job
The adapter.Fill and ExecuteNonQuery do the same job here and that's why your updates happening twice
Make use of parameterization while dealing with user inputs to avoid exceptions
For parsing integers use int.TryParse instead for Convert.ToInt32
I think the following code would help you to do the same function in a smarter way:
int currentBalance = 0;
if(int.TryParse(txtAdd.Text, out currentBalance))
{
string querSql = "Update [Order] set Balance = Balance + #balance," +
" Card = #card where email = #email"
using (SqlConnection dbConn = new SqlConnection("connectionString here"))
{
dbConn.Open();
using (SqlCommand sqlCommand = new SqlCommand(querySql, dbConn))
{
sqlCommand.Parameters.Add("#balance", SqlDbType.int).value = currentBalance;
sqlCommand.Parameters.Add("#card", SqlDbType.VarChar).value = card.Text;
sqlCommand.Parameters.Add("#email", SqlDbType.VarChar).value = email;
sqlCommand.ExecuteNonQuery();
}
}
}
Please note: YOu are parsing the balance as an integer value, so I assume the column Balance is an integer field in the database, if not make use of corresponding datatype for the parameter #balance also update the parsing technique

As per the documentation:
SqlDataAdapter(SqlCommand)
Initializes a new instance of the SqlDataAdapter class with the specified SqlCommand as the SelectCommand property.
What is going wrong in your code?
Actually you are passing SqlDataAdapter your update query as the Select command. So now when you will use this instance of SqlDataAdapter to Fill your datatable then actually you are executing your Update command. Look at the following code along with comments to see what is going wrong:
DataTable dr = new DataTable();
string email = txtEmail.Text;
SqlConnection con = new SqlConnection(Ws.Con);
con.Open();
int s = Convert.ToInt32(add.Text);
SqlCommand cmd = new SqlCommand("Update [Order] set Balance=Balance+'" + s + "',Card='" + card.Text + "' where email=#email ", con);
cmd.Parameters.AddWithValue("email", email);
SqlDataAdapter sda = new SqlDataAdapter(cmd);//The Select command for SqlDataAdapter
//is actually now the update command specified by cmd instnace of SqlCommand
DataTable dt = new DataTable();
sda.Fill(dt);//here SqlDataAdapter will execute it's Select command which is actually set
//to an update statement so your record will be updated
int i = cmd.ExecuteNonQuery();//and here again the update command is being executed now
//directly using the SqlCommand cmd instance and thus your record gets updated twice
con.Close();
Fixed Code:
DataTable dr = new DataTable();
string email = txtEmail.Text;
SqlConnection con = new SqlConnection(Ws.Con);
con.Open();
int s = Convert.ToInt32(add.Text);
SqlCommand cmd = new SqlCommand("Update [Order] set Balance=Balance+'" + s + "',Card='" + card.Text + "' where email=#email ", con);
cmd.Parameters.AddWithValue("email", email);
//Create a new SqlComamnd
SqlCommand selectCommand = new SqlCommand("Select * from [Order]");
//Put the newly created instance as SelectCommand for your SqlDataAdapter
SqlDataAdapter sda = new SqlDataAdapter(selectCommand);
DataTable dt = new DataTable();
sda.Fill(dt);
int i = cmd.ExecuteNonQuery();
con.Close();
Hope this help and do have a look at the documentation for better understanding of the SqlDataAdapter and DataTable. Thanks.

insert,update in single button clickin winforms

I am not getting, how to do insert and update of the data in C# WinForms on single button click.
private void save_Click(object sender, EventArgs e)
{
SqlConnection cn = new SqlConnection();
cn.ConnectionString = "data source=Sai;database=kaur; user id=sa;password=azxc;";
cn.Open();
string gen;
if (radioButton1.Checked == true)
gen = "Male";
else
gen = "Female";
string clas = null;
clas = comboBox1.Text;
string section = null;
section = comboBox2.Text;
SqlCommand cmd = new SqlCommand();
cmd.CommandText = "insert into studetail values('" + textBox1.Text + "','" + textBox2.Text + "','" + gen + "','" + textBox3.Text + "','" + clas + "','" + section + "')";
cmd.Connection = cn;
int n = cmd.ExecuteNonQuery();
if (n > 0)
MessageBox.Show(n + " Row Inserted.");
else
MessageBox.Show("Insertion failed.");
SqlDataAdapter da = new SqlDataAdapter("select * from studetail ", cn);
DataTable dt = new DataTable();
da.Fill(dt);
dataGridView1.DataSource = dt;

You can add a deletion before the insertion:
private void save_Click(object sender, EventArgs e)
{
DeletePerson(id); // add this
SqlConnection cn = new SqlConnection();
...
}
public void DeletePerson(int id)
{
using(SqlConnection connection = new SqlConnection(credentials))
{
connection.Open();
SqlCommand cmd = new SqlCommand();
cmd.Connection = connection;
cmd.CommandText = "delete from studetail where someUniqeIdColumn = " + id;
cmd.ExecuteNonQuery();
}
}
Using responsible to dispose the connection.
Consider using Entity Framework or LINQ to SQL.
You are exposed to SQL injection.

First off the SQL query isn't quite right. It should look something like the following:
INSERT INTO studetail (columnName1, columnName2, ...columnNameN)
VALUES (value1, value2, ...valueN);
Where the column names are the columns where you want data to be inserted, and the values are the data you want inserted into said columns.
You should also be disposing the connection by wrapping the connection within a using statement.
using(var con = new SqlConnection(connectionString))
{
con.Open();
//rest of code that needs a connection here
}
Additionally, you need to be wary of SQL injection. I highly suggest reading this example from the MSDN website. It will give you an example of using an SQL Update and avoiding SQL injection with use of SqlCommand.Paramaters property.
You should also have a Primary Key in your database tables, if you don't already, so you can uniquely identify each record in a table.
To do an update and a save on the same button, you will need to check if a row already exists for the data that is being edited. This when a Primary comes in handy. You will want to check your database to see if a record already exists
SELECT 1 FROM studetail WHERE <Condition>
The WHERE condition will be the way you uniquely identify (a Primary Key) a row in your table. If the rows in the table are uniquely identified, the above SQL statement will return 1 if a value exists, which means you can UPDATE or 0 if no record exists, so you can INSERT

My primary key is not getting updated

When I tried to update my primary key from the textbox, it's not getting updated. The rest of the columns are updated fine. Please help me.
I am not getting any error. Nothing.. When I try to update the part number.. it's not updating.. Simply going back to the previous value.
My code to update value to database:
private void Update_Click(object sender, EventArgs e)
{
try
{
SqlConnection con = new SqlConnection(#"Data Source=SREEJITHMOHA492\SQLEXPRESS;Initial Catalog=cndb;Integrated Security=True");
con.Open();
SqlCommand cmd = new SqlCommand(#"update cncinfo set part='" + this.file_NameTextBox.Text
+ "',drawings='" + this.drawingsTextBox.Text + "',draftpath='"
+ this.gcodeTextBox.Text + "',comments='" + this.commentsTextBox.Text
+ "' where part='" + dataGridView1.Rows[0].Cells[0].Value.ToString() + "' ;", con);
}
catch (System.Exception ex)
{
MessageBox.Show(ex.Message);
}
}
void load_table()
{
SqlConnection con = new SqlConnection(#"Data Source=SREEJITHMOHA492\SQLEXPRESS;Initial Catalog=cndb;Integrated Security=True");
con.Open();
SqlCommand cmd = new SqlCommand("select part as 'Part Number',drawings as 'Drawings',draftpath as 'G-Code Path',releasepath as 'Release Path',comments as 'Comments' from cncinfo ;", con);
cmd.ExecuteNonQuery();
con.Close();
try
{
SqlDataAdapter sda = new SqlDataAdapter();
sda.SelectCommand = cmd;
dbddataset = new DataTable();
sda.Fill(dbddataset);
BindingSource bSource = new BindingSource();
bSource.DataSource = dbddataset;
dataGridView1.DataSource = bSource;
sda.Update(dbddataset);
}
catch (System.Exception ex)
{
MessageBox.Show(ex.Message);
}
}
Thanks in advance

First, use parameters. See Bobby Tables.
Second, your update statement uses the same input for both the set and where clauses:
#"update cncinfo set part='" + this.file_NameTextBox.Text + "',...' where part='" + this.file_NameTextBox.Text + "' ;"
How do you plan to change the value of the part when you select only the row that already has the new value? You need to use both an old and new value:
#"update cncinfo set part='" + this.file_NameTextBox.Text + "',...' where part='" + oldPart + "' ;"
Finally, ExecuteNonQuery returns the number of rows affected. If you checked the value you would find that it is 1 when you update a row and 0 when you try to change the value of part unless there is already a row with the new part value (in which case you update that row instead of generating an error on a duplicate part).
You should also consider using a using statement for your connections and commands.

More efficient way of running multiple update queries on an Access database?

I have multiple queries like this right now which involve updating different fields of the same row in an Access database:
//Update database
string updatequery = "UPDATE [table] SET [Last10Attempts] = ? WHERE id = ?";
OleDbConnection con = new OleDbConnection(#"Provider=Microsoft.ACE.OLEDB.12.0;" + #"Data Source=" + "database.accdb");
con.Open();
OleDbDataAdapter da = new OleDbDataAdapter(updatequery, con);
var accessUpdateCommand = new OleDbCommand(updatequery, con);
accessUpdateCommand.Parameters.AddWithValue("Last10Attempts", last10attempts);
accessUpdateCommand.Parameters.AddWithValue("ID", currentid + 1);
da.UpdateCommand = accessUpdateCommand;
da.UpdateCommand.ExecuteNonQuery();
//update last10attemptssum
updatequery = "UPDATE [table] SET [Last10AttemptsSum] = ? WHERE id = ?";
accessUpdateCommand = new OleDbCommand(updatequery, con);
accessUpdateCommand.Parameters.AddWithValue("Last10AttemptsSum", counter);
accessUpdateCommand.Parameters.AddWithValue("ID", currentid + 1);
da.UpdateCommand = accessUpdateCommand;
da.UpdateCommand.ExecuteNonQuery();
//increment totalquestionattempt
updatequery = "UPDATE [table] SET [total-question-attempts] = ? WHERE id = ?";
accessUpdateCommand = new OleDbCommand(updatequery, con);
accessUpdateCommand.Parameters.AddWithValue("total-question-attempts", questionattempts + 1);
accessUpdateCommand.Parameters.AddWithValue("ID", currentid + 1);
da.UpdateCommand = accessUpdateCommand;
da.UpdateCommand.ExecuteNonQuery();
con.Close();
I was wondering if there is a more efficient way of running these update queries - ie. combining them into one query.

There is no need to use an OleDbDataAdapter in your context above. You could use a simple command and execute it
Said that, an Update sql statement can update more than one field. Just write
string updatequery = #"UPDATE [table] SET [Last10Attempts] = ?,
[Last10AttemptsSum] = ?,
[total-question-attempts] = ?
WHERE id = ?";
using(OleDbConnection con = new OleDbConnection(.........))
using(OleDbCommand cmd = new OleDbCommand(updatequery, con))
{
con.Open();
cmd.Parameters.AddWithValue("Last10Attempts", last10attempts);
cmd.Parameters.AddWithValue("Last10AttemptsSum", counter);
cmd.Parameters.AddWithValue("total-question-attempts", questionattempts + 1);
cmd.Parameters.AddWithValue("ID", currentid + 1);
cmd.ExecuteNonQuery();
}
The only thing to keep present when working with OleDb is the fact that the parameters are used in the exact order in which the parameter placeholder appears in the command text. So they should be added to the parameter collection in the order expected by the command text

Datagrid filter in c# using sql server

How to filter data in datagrid for example if you select the combo box in student number then input 1001 in the text field. All records in 1001 will appear in datagrid. I am using sql server
private void button2_Click(object sender, EventArgs e)
{
if (cbofilter.SelectedIndex == 0)
{
string sql;
SqlConnection conn = new SqlConnection();
conn.ConnectionString = "Server= " + Environment.MachineName.ToString() + #"\; Initial Catalog=TEST;Integrated Security = true";
SqlDataAdapter da = new SqlDataAdapter();
DataSet ds1 = new DataSet();
ds1 = DBConn.getStudentDetails("sp_RetrieveSTUDNO");
sql = "Select * from Test where STUDNO like '" + txtvalue.Text + "'";
SqlCommand cmd = new SqlCommand(sql, conn);
cmd.CommandType = CommandType.Text;
da.SelectCommand = cmd;
da.Fill(ds1);
dbgStudentDetails.DataSource = ds1;
dbgStudentDetails.DataMember = ds1.Tables[0].TableName;
dbgStudentDetails.Refresh();
}
else if (cbofilter.SelectedIndex == 1)
{
//string sql;
//SqlConnection conn = new SqlConnection();
//conn.ConnectionString = "Server= " + Environment.MachineName.ToString() + #"\; Initial Catalog=TEST;Integrated Security = true";
//SqlDataAdapter da = new SqlDataAdapter();
//DataSet ds1 = new DataSet();
//ds1 = DBConn.getStudentDetails("sp_RetrieveSTUDNO");
//sql = "Select * from Test where Name like '" + txtvalue.Text + "'";
//SqlCommand cmd = new SqlCommand(sql,conn);
//cmd.CommandType = CommandType.Text;
//da.SelectCommand = cmd;
//da.Fill(ds1);
// dbgStudentDetails.DataSource = ds1;
//dbgStudentDetails.DataMember = ds1.Tables[0].TableName;
//ds.Tables[0].DefaultView.RowFilter = "Studno = + txtvalue.text + ";
dbgStudentDetails.DataSource = ds.Tables[0];
dbgStudentDetails.Refresh();
}
}

It's difficult to answer pricisely to a vague question. I guess that you'll have to adapt your SQL query with a WHERE statement containing the user input.
If 'student number' is selected in the combo box, query like this (numbers starting with):
SELECT id, name, number FROM students WHERE number LIKE #search + '%'
If 'student name' is selected, use another query (names containing):
SELECT id, name, number FROM students WHERE name LIKE '%' + #search + '%'
Please explain in what sense C# is concerned.

You don't say what is wrong with the code you commented out. You also don't say what type the Studno column is.
Have you tried something like:
ds1.Tables[0].DefaultView.RowFilter = "Studno = '" + txtvalue.text + "'";