I have this code:
private void FirmaEkleB_Click(object sender, EventArgs e)
{
string query = "INSERT INTO FIRMATABLE VALUES (#CompanyName)";
SqlConnection sqlconnection = new SqlConnection(connectionString);
SqlCommand command = new SqlCommand(query, sqlconnection);
Form1 LoginForm = new Form1();
sqlconnection.Open();
command.Parameters.AddWithValue("#CompanyName", FirmaIsmiTextbox.Text);
command.ExecuteScalar();
SqlCommand com2 = new SqlCommand("Select FirmaIsmi FROM FIRMATABLE WHERE ID = 9", sqlconnection);
MessageBox.Show(com2.ExecuteScalar().ToString());
LoginForm.fillFirmaList();
}
fillFirmaList() looks like this:
public void fillFirmaList()
{
connection = new SqlConnection(connectionString);
SqlCommand command = new SqlCommand("SELECT * FROM FirmaTable", connection);
SqlDataAdapter adapter = new SqlDataAdapter(command);
DataTable firmaTable = new DataTable();
adapter.Fill(firmaTable);
FirmaCombo.DataSource = firmaTable;
FirmaCombo.DisplayMember = "FirmaIsmi";
FirmaCombo.ValueMember = "Id";
}
I don't know what I'm doing wrong but I can't seem get my combobox to update from the table I have. The manually added rows show up but not the one that I add
Keep in mind that I'm just starting out in SQL Server and database stuff.
If more info is needed tell me.
Change your Insert query to
INSERT INTO FIRMATABLE (FirmaIsmi) VALUES (#CompanyName)
You need to include all your column names for which you are adding the VALUES.
And
change ExecuteScalar to command.ExecuteNonQuery().
Add try-catch block and see what exception does it throws after ExecuteNonQuery
Related
I'm working on a school development project and I'm quite new to development. I have been reading online but can't find the answer I'm looking for.
So far I have created a listbox in my Windows Forms application which I want to select all the values from one of my columns, and these should work as a inparameter to display data in my dataGridView based on the parameter.
I have created 70% of my project and this functionality is what is left. My database is in Azure and I can write to it and add new rows, but I can't read anything to my application when I run it.
code for listview, at first I just want to be able to select. Later on somehow write the choosen parameter to a variable that I can use as a condition in my dataGridView.
This is the code for my gridview so far I just want to display all data in it, but it's not showing anything.
namespace MyNamespace
{
public partial class CompanyForm : Form
{
public CompanyForm()
{
InitializeComponent();
}
//Connection String
string cs = ConfigurationManager.ConnectionStrings["ConnectionString"].
ConnectionString;
private void createCompany_Click_1(object sender, EventArgs e)
{
if (textBoxCompanyName.Text == "")
{
MessageBox.Show("Fill information");
return;
}
using (SqlConnection con = new SqlConnection(cs))
{
//Create SqlConnection
con.Open();
SqlCommand cmd = new SqlCommand
(
"insert into dbo.Company (companyName)
values(#companyName)", con);
cmd.Parameters.AddWithValue
(
"#companyName",
textBoxCompanyName.Text);
SqlDataAdapter adapt = new SqlDataAdapter(cmd);
DataSet ds = new DataSet();
adapt.Fill(ds);
MessageBox.Show("GJ");
}
}
// The code that is not filling my datagrid
private void dataEmployees_Load()
{
using (SqlConnection con = new SqlConnection(cs))
{
con.Open();
SqlCommand cmd = new SqlCommand
(
"Select fname,ename FROM dbo.Users", con
);
SqlDataReader dr = cmd.ExecuteReader();
DataTable dt = new DataTable();
dt.Load(dr);
dataEmployees.DataSource = dt;
}
}
}
}
My connection string is working it's already being able to insert data to the tables that I have.
The problem why you Grid isn't shown any data is that you try to bind a SqlDataReader to it. This isn't working, because the Grid doesn't support this as DataSource.
What you need as DataSource is DataTable, IList<T>, IBindingList<T>. In your case the DataTable would be the easiest solution. Try this out:
protected void DataEmployees()
{
using (SqlConnection con = new SqlConnection(cs))
{
con.Open();
SqlCommand cmd = new SqlCommand
(
"Select firstname,lastname FROM employees",con
);
SqlDataReader dr = cmd.ExecuteReader();
DataTable dt = new DataTable();
dt.Load(dr);
dataEmployees.DataSource = dt;
}
}
Notice that Methods are written Uppercase in C#. Further notice that you don't need to close the connection manually if you use a using-block. On the end of the using-block it's automatically closed/disposed.
I have stored some number data under column name Value in the tblV table of my database. I want to put the data from that column Value into textbox1.
But whenever I click the button it shows Column 'Value' does not belong to table error even though there is column Value in the table. What is causing this problem?
The first one is class and second one is the code on button click event.
public DataTable GetMaxno(decimal Licenseno)
{
SqlConnection con = new SqlConnection("Data Source=(LocalDB)\\MSSQLLocalDB; Integrated Security=True; Initial Catalog=sudipDB;");
string sql = "select Max(Value) from tblv where Licenseno=#licenseno";
SqlCommand cmd = new SqlCommand(sql, con);
cmd.Parameters.AddWithValue("#Licenseno",Licenseno );
SqlDataAdapter da = new SqlDataAdapter(cmd);
DataTable DT = new DataTable();
da.Fill(DT);
return DT;
}
tryv tv = new tryv();
private void button1_Click(object sender, EventArgs e)
{
DataTable dt = tv.GetMaxno(Convert.ToDecimal(textBox2.Text));
if (dt.Rows.Count > 0)
{
textBox1.Text= dt.Rows[0]["Value"].ToString();
}
}
Reason might be that your query does not return any aliases as Value. You can solve this with select Max(Value) as Value but instead of that, use ExecuteScalar instead which is exactly what you want. It returns first column of the first row.
A few things more;
Use using statement to dispose your connection and command.
Do not use AddWithValue. It may generate unexpected and surprising result sometimes. Use Add method overloads to specify your parameter type and it's size.
public int GetMaxno(decimal Licenseno)
{
using(var con = new SqlConnection("Data Source=(LocalDB)\\MSSQLLocalDB; Integrated Security=True; Initial Catalog=sudipDB;")
using(var cmd = con.CreateCommand())
{
cmd.CommandText = "select Max(Value) from tblv where Licenseno = #licenseno";
cmd.Parameters.Add("#licenseno", SqlDbType.Decimal).Value = Licenseno;
con.Open();
return (int)cmd.ExecuteScalar();
}
}
Then you can do;
textBox1.Text = tv.GetMaxno(Convert.ToDecimal(textBox2.Text)).ToString();
try
string sql = "select Max(Value) as Value from tblv where Licenseno=#licenseno";
I'm stuck with my changes not getting saved to the SQL Server database.
I can read the database properly, and when calling RefreshGrid() that refreshes from the database, the gridview updates correctly. But not when restarting the program or checking the actual database, then the changes are gone.
I would normally use Entity Framework for this, but sometimes one needs to learn other ways.
private string conString = ConfigurationManager.ConnectionStrings["RewardsConnectionString"].ConnectionString;
private RewardsDS rewardsDset = new RewardsDS();
private SqlDataAdapter CreateDataAdapter(SqlConnection conn)
{
// Build the selection query.
SqlDataAdapter rewardsAdapter = new SqlDataAdapter();
SqlCommand selectCommand = new SqlCommand("SELECT * FROM Purchases", conn);
rewardsAdapter.SelectCommand = selectCommand;
// Build the insertion query
SqlCommand insertCommand = new SqlCommand(
#"INSERT INTO Purchases (PurchaseDate, Amount, CustomerId)
VALUES (#PurchaseDate, #Amount, #CustomerId)", conn);
insertCommand.Parameters.Add("#PurchaseDate", SqlDbType.DateTime, 0, "PurchaseDate"); // Not sure about this zero ...
insertCommand.Parameters.Add("#Amount", SqlDbType.Decimal, 0, "Amount");
insertCommand.Parameters.Add("#CustomerId", SqlDbType.Int, 0, "CustomerId");
rewardsAdapter.InsertCommand = insertCommand;
// Build the update query
SqlCommand updateCommand = new SqlCommand(
#"UPDATE Purchases SET Amount = #Amount, PurchaseDate = #PurchaseDate WHERE PurchaseId = #PurchaseId", conn);
updateCommand.Parameters.Add("#Amount", SqlDbType.Decimal, 0, "Amount");
updateCommand.Parameters.Add("#PurchaseDate", SqlDbType.DateTime, 0, "PurchaseDate");
SqlParameter param = updateCommand.Parameters.Add("#PurchaseId", SqlDbType.Int, 0, "PurchaseId");
param.SourceVersion = DataRowVersion.Original;
rewardsAdapter.UpdateCommand = updateCommand;
// Build the delete query
SqlCommand deleteCommand = new SqlCommand(
"DELETE FROM Purchases WHERE PurchaseId = #PurchaseId", conn);
param = deleteCommand.Parameters.Add("#Id", SqlDbType.Int, 0, "PurchaseId");
param.SourceVersion = DataRowVersion.Original;
rewardsAdapter.DeleteCommand = deleteCommand;
return rewardsAdapter;
}
// Gets changes and saves them to the database.
private void SaveChanges()
{
using (SqlConnection conn = new SqlConnection(conString))
{
var fadapter = CreateDataAdapter(conn);
conn.Open();
DataSet changes = rewardsDset.GetChanges();
try
{
fadapter.Update(changes, "Purchases");
}
catch (Exception ex)
{
MessageBox.Show("There are no updates to be saved");
}
conn.Close();
rewardsDset.AcceptChanges();
}
}
// Refresh the dataGridView from the database
private void RefreshGrid()
{
rewardsDset.Clear();
using (SqlConnection conn = new SqlConnection(conString))
{
conn.Open();
SqlDataAdapter myAdapter = new SqlDataAdapter("SELECT * FROM Purchases", conn);
myAdapter.Fill(rewardsDset, "Purchases");
conn.Close();
dataGridView1.DataSource = null;
this.dataGridView1.DataSource = rewardsDset.Tables["Purchases"];
}
}
You simply have to execute the queries:
rewardsAdapter.InsertCommand.ExecuteNonQuery();
I will start by apologizing for wasting anyone's time. Finally found what was causing this error and it was far more basic than I thought and not at all where I've been trying to look for solutions.
I've made an embarrassing mistake regarding the connection string, but if someone repeats my mistake this was it:
I've been using the connection string to the DataSet, and not to the actual database ...
Adding the proper connection string certainly solved my problem, and was of course impossible for anyone to see with only the code I posted above.
I am trying to delete selected data from datagrid and database at the same time when user clicks on "Delete". It is not working and error message shows that "Index was out of range. Must be non-negative and less than the size of the collection.Parameter name: index"
Can anyone help me out this coding.
private void btnDeleteCustomer_Click(object sender, EventArgs e)
{
string strSqlConnection = #"Data Source = KK\SQLEXPRESS; Integrated Security = SSPI; Initial Catalog = JeanDB";
if ((dgvCustomerView.Rows.Count>0) && (dgvCustomerView.SelectedRows[1].Index != dgvCustomerView.Rows.Count))
{
SqlConnection sqlconn = new SqlConnection(strSqlConnection);
DataSet dsCustomers = new DataSet();
int iCustomerID = Convert.ToInt32(dgvEmpView.SelectedRows[0].Cells[0].Value.ToString());
string QueryDelCus = #"Delete from dbo.Customers WHERE CustomerID = #iCustomerID";
SqlDataAdapter sdaCustomer = new SqlDataAdapter(QueryDelCus, sqlconn);
sqlconn.Open();
DataTable dtEmployee = new DataTable("Customers");
sdaCustomer.Fill(dsCustomers, "Customers");
sqlconn.Close();
dgvEmpView.Rows.RemoveAt(dgvEmpView.SelectedRows[0].Index);
MessageBox.Show("Deleted Successfully");
}
}
Instead of Remove you can rebind grid:
dgvEmpView.DataSource = dsCustomers;
dgvEmpView.DataBind();
MessageBox.Show("Deleted Successfully");
and for deletion ExecuteNonQuery is used:
SqlCommand cmd = new SqlCommand(QueryDelCus, sqlconn);
sqlconn.Open();
cmd.ExecuteNonQuery();
Unless you have two rows selected referencing the SelectedRows[1] is wrong. The array indexes start always with zero. (Probably it is just a type because the other lines references correctly the row to be deleted)
if ((dgvCustomerView.Rows.Count>0) &&
(dgvCustomerView.SelectedRows[0].Index != dgvCustomerView.Rows.Count))
{
....
but then, to delete the row in the database, you don't need to use an SqlDataAdapter.
You could work directly with a SqlCommand
int iCustomerID = Convert.ToInt32(dgvEmpView.SelectedRows[0].Cells[0].Value.ToString());
string QueryDelCus = #"Delete from dbo.Customers WHERE CustomerID = #iCustomerID";
SqlCommand cmd = new SqlCommand(QueryDelCus, sqlconn);
cmd.Parameters.AddWithValue("#iCustomerID", iCustomerID);
sqlconn.Open();
cmd.ExecuteNonQuery();
finally you could simply remove the selected row from the grid without further query
dgvEmpView.Rows.RemoveAt(dgvEmpView.SelectedRows[0].Index);
If do not use sql parameters then use plain sql query.
DataSet dsCustomers = new DataSet();
int iCustomerID = Convert.ToInt32(dgvEmpView.SelectedRows[0].Cells[0].Value.ToString());
string QueryDelCus = #"Delete from dbo.Customers WHERE CustomerID = "+ iCustomerID.ToString();
SqlDataAdapter sdaCustomer = new SqlDataAdapter(QueryDelCus, sqlconn);
I'm coding a simple application using c# asp.net. I'm getting the averages of columns. How can I get the individual values from the result and display it in a new label (label1, label2, label3....)?
I tried ExecuteScalar().ToString(); but it returns only the first column.
Below is my code:
SqlConnection con;
con = new SqlConnection("Data Source=.\\SQLEXPRESS;AttachDbFilename=|DataDirectory|\\STATDB.MDF;Integrated Security=True;User Instance=True");
SqlCommand com = new SqlCommand();
SqlDataAdapter da = new SqlDataAdapter();
string result = "SELECT AVG(p_tan) AS p_tang, AVG(e_tan) AS e_tang, AVG(p_rel) AS p_reli FROM statistics";
SqlCommand showresult = new SqlCommand(result, con);
con.Open();
Label1.Text = showresult.ExecuteScalar().ToString();
//Label2.Text = p_tang
//Label3.Text = e_tang
//Label4.Text = p_reli
con.Close();
Any help will be appreciated.
Use showresult.ExecuteReader() and then iterate over the row to get the values
SqlDataReader reader=showresult.ExecuteReader();
while (reader.Read())
{
Label1.Text= reader["p_tang"].ToString().Trim();
Label2.Text= reader["e_tang"].ToString().Trim();
Label3.Text= reader["p_reli"].ToString().Trim();
}
ExecuteScalar will only pull one value. You will need do either use a DataReader or DataAdapter to get multiple values from the database.