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How to search data in gridview using a TextBox value with an Oracle Database

I am trying to show Oracle Data in a DataGridView in my Windows Form Application but it just returns a grey blank view. My code for this currently is:
string insertquery = "select * from Candidate where CandidateName like '"+ txtBoxSearchData.Text +"%'";
OracleConnection con = new OracleConnection(oradb);
con.Open();
OracleCommand cmd = new OracleCommand();
cmd.Connection = con;
cmd.CommandText = insertquery;
try
{
OracleDataReader reader = cmd.ExecuteReader();
OracleDataAdapter orada = new OracleDataAdapter(cmd);
DataTable dataTable = new DataTable();
orada.Fill(dataTable);
dataTable.Load(reader);
BindingSource bSource = new BindingSource();
bSource.DataSource = dataTable;
dataGridViewSearch.DataSource = bSource;
orada.Update(dataTable);
}
catch(ArgumentException ex)
{
MessageBox.Show("Error: " + ex.Message);
}
catch(OracleException ex1)
{
MessageBox.Show("Error: " + ex1.Message);
}
finally
{
cmd.Dispose();
con.Dispose();
}
}
I am positive I do not require all those functions in my Try statement but I have come across many different methods to do this - I just included all of those into my code to experiment. The connection string is correct too as I have succeeded in adding data into the tables through queries in another part of my application.

Doing something like the following should be enough. There should be no need for an OracleDataAdapter or BindingSource. Just can't test it here, as I do not have an Oracle database around.
public void fillDataGrid()
{
try
{
using(OracleConnection connection = new OracleConnection("connectstring"))
using(OracleCommand cmd = new OracleCommand("select * from my super table", connection ))
{
connection .Open();
using(OracleDataReader oracleDataReader = cmd.ExecuteReader())
{
DataTable dataTable = new DataTable();
dataTable.Load(oracleDataReader );
myDataGrid.DataSource = dataTable;
}
}
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
}
}

How to update data from DataGridView to database? ERROR - Cannot insert value NULL

I'm trying to update data from DataGridView to my database. While I was looking for the solution of this problem on google, I noticed that all of the solutions are managed by using class variables (for DataTable,SqlDataAdapter,...). I'm trying to do this just by using function variables.
This is how I loaded data to DataGridView:
private void LoadDataGridView(int ID)
{
try
{
SqlConnection connection = new SqlConnection(connString);
SqlCommand cmd = new SqlCommand("SELECT SENTENCE FROM Sentences WHERE CategoryID = #ID",connection);
cmd.Parameters.Add("#ID",SqlDbType.Int).Value = ID;
DataTable dataTable = new DataTable();
SqlDataAdapter dataAdapter = new SqlDataAdapter(cmd);
dataAdapter.Fill(dataTable);
DataGridView.DataSource = dataTable;
}
catch (Exception)
{
MessageBox.Show("ERROR WHILE CONNECTING TO DATABASE!");
}
}
DataGridView is showing just those sentences that match particular ID.
This is what I have tried so far:
private void RefreshBtn_Click(object sender, EventArgs e)
{
try
{
SqlConnection connection = new SqlConnection(connString);
SqlCommand cmd = new SqlCommand("SELECT SENTENCE FROM Sentences WHERE CategoryID IN(#CategoryID)", connection);
cmd.Parameters.Add("#CategoryID",SqlDbType.Int).Value = CategoryID;
SqlDataAdapter dataAdapter = new SqlDataAdapter(cmd);
SqlCommandBuilder cmdBuilder = new SqlCommandBuilder(dataAdapter);
dataAdapter.Update(dataTable);
}
catch (Exception)
{
MessageBox.Show("ERROR WHILE CONNECTING WITH DATABASE!");
}
}
This is the error that comes up:
Cannot insert value NULL into column CategoryID, table ...;column does not allow nulls.Insert fails. The statement has been terminated.

if your Id data type is int ,you don't need put it inside "".
private void RefreshBtn_Click(object sender, EventArgs e)
{
try
{
string connString;//WHAT EVER IT IS
string Query=string.Format(#"SELECT QUESTION FROM Questions WHERE CategoryID = '{0}'",CategoryID);
SqlConnection connection = new SqlConnection(connString);
SqlCommand cmd = new SqlCommand(Query, connection);
connection.Open();
cmd.ExecuteNonQuery();
SqlDataAdapter dataAdapter = new SqlDataAdapter(cmd,connString);
DataTable DataTable=new DataTable();
dataAdapter.Fill(DataTable);
datagridview1.DataSource=DataTable;
}
catch (Exception)
{
MessageBox.Show("ERROR WHILE CONNECTING WITH DATABASE!");
}
catch (SqlException)
{
MessageBox.Show("SqL Error!");
}
}

SOLUTION of my problem:
Firstly, I have shown all columns of database table in DataGridView and then I have hided Primary Key column and CategoryID column. That is shown in the following code:
private void LoadDataGridView(int ID)
{
try
{
SqlConnection connection = new SqlConnection(connString);
SqlCommand cmd = new SqlCommand();
cmd.CommandText = "SELECT * FROM Sentences WHERE CategoryID = #ID";
cmd.Connection = connection;
cmd.Parameters.Add("#ID",SqlDbType.Int).Value = ID;
dataTable = new DataTable();
SqlDataAdapter dataAdapter = new SqlDataAdapter(cmd);
dataAdapter.Fill(dataTable);
dataGridView.DataSource = dataTable;
dataGridView.Columns[0].Visible = false;
dataGridView.Columns[2].Visible = false;
}
catch (Exception)
{
MessageBox.Show("ERROR WHILE CONNECTING WITH DATABASE!");
}
}
Then, I have set default value only for CategoryID column, because Primary Key column has an option of Auto - Increment. That is show in the following code:
private void dataGridView_DefaultValuesNeeded(object sender, DataGridViewRowEventArgs e)
{
e.Row.Cells["CategoryID"].Value = CategoryID;
}
The last thing I have done is implement the code for RefreshBtn (the following code is practically the same as the code in question):
private void RefreshBtn_Click(object sender, EventArgs e)
{
try
{
SqlConnection connection = new SqlConnection(connString);
SqlCommand cmd = new SqlCommand();
cmd.CommandText = "SELECT * FROM Questions WHERE CategoryID = #CategoryID";
cmd.Connection = connection;
cmd.Parameters.Add("#CategoryID", SqlDbType.Int).Value = CategoryID;
SqlDataAdapter dataAdapter = new SqlDataAdapter(cmd);
SqlCommandBuilder cmdBuilder = new SqlCommandBuilder(dataAdapter);
dataAdapter.Update(dataTable);
}
catch (Exception)
{
MessageBox.Show("ERROR WHILE CONNECTING WITH DATABASE !");
}
}

OleDbDataAdapter Fill method bad performance

I'm using OleDbDataAdapter class to get data from an Access (.mdb) file.
OleDbConnection con = new OleDbConnection(#"Provider=Microsoft.Jet.OLEDB.4.0;Data Source="+Environment.CurrentDirectory+"\\Data.mdb;Jet OLEDB:Database Password=pass");
OleDbCommand com = new OleDbCommand(query, con);
DataTable dt = new DataTable();
con.Open();
OleDbDataAdapter oda = new OleDbDataAdapter(com);
oda.Fill(dt);
oda.Dispose();
com.Parameters.Clear();
con.Close();
return dt;
The problem is that by debugging I found out, oda.Fill(dt) takes a very long time to execute. (around 10 seconds)
I have 50,000 records in the database and I only need to retrieve 1 row.
Please help. Thank you in advance.

If all you need is one row try using a data reader as shown below, of your you will need to adjust pieces like database name, field list etc.
Note I write output to the IDE Output window so have it open when trying this with your code/data.
public partial class Form1 : Form
{
private void button1_Click(object sender, EventArgs e)
{
int id = 0;
if (int.TryParse(textBox1.Text, out id))
{
OleDbConnectionStringBuilder Builder = new OleDbConnectionStringBuilder();
Builder.Provider = "Microsoft.Jet.OLEDB.4.0";
Builder.DataSource = Path.Combine(Application.StartupPath, "Database1.mdb");
using (OleDbConnection cn = new OleDbConnection(Builder.ConnectionString))
{
string selectStatement = "SELECT UserName, JoinMonth FROM Users WHERE Identifier = #Identifier";
using (OleDbCommand cmd = new OleDbCommand { CommandText = selectStatement, Connection = cn })
{
cmd.Parameters.Add(new OleDbParameter { ParameterName = "#Identifier", DbType = DbType.Int32, Value = id });
cn.Open();
OleDbDataReader dr = cmd.ExecuteReader();
if (dr.HasRows)
{
dr.Read();
Console.WriteLine("{0} - {1}", dr.GetString(0), dr.GetString(1));
}
else
{
Console.WriteLine("Not located");
}
}
}
}
}
}

Winforms comboboxes and parameterized stored procedure

In my tblSates Table, I have a column named Monat with these three values
[01.2016, 02.2016 and 03.2016] and I want to fetch these values in a combobox.
I am getting the values but just two of them instead of all three.
Here is my code:
private void FillCombobox2()
{
string S = ConfigurationManager
// TSQL-Statement
SqlCommand cmd = new SqlCommand();
cmd.Connection = con;
cmd.CommandText = ("SELECT DISTINCT Monat from tblSales");
SqlDataReader myReader;
try
{
con.Open();
myReader = cmd.ExecuteReader();
if (myReader.Read())
{
DataTable dt = new DataTable();
dt.Load(myReader);
combobox1.DisplayMember = "Monat";
combobox1.ValueMember = "Monat";
combobox1.DataSource = dt;
combobox1.SelectedIndex = -1;
}
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
finally
{
con.Close();
}
}
Will appreciate any help or an alternative solution.

I removed reader.Read and then call which advanced the position (and skipped one of my three records). Alternatively I could have used if (myReader.HasRows).
private void FillCombobox2()
{
string S = ConfigurationManager
// TSQL-Statement
SqlCommand cmd = new SqlCommand();
cmd.Connection = con;
cmd.CommandText = ("SELECT DISTINCT Monat from tblSales");
//SqlDataReader myReader;
try
{
con.Open();
SqlDataAdapter ad = new SqlDataAdapter(cmd);
DataTable dt = new DataTable();
ad.Fill(dt)
combobox1.DisplayMember = "Monat";
combobox1.ValueMember = "Monat";
combobox1.DataSource = dt;
combobox1.SelectedIndex = -1;
}
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
finally
{
con.Close();
}
}

Populating ComboBox with Data

I want to display the items in my database inside the combo box after the radio option is been selected. when i tried this nothing was displayed in the combo box. please kindly help
private void chkDetailsButton_Click(object sender, EventArgs e)
{
if (radioButtonA.Checked)
{
OleDbConnection connect = db.dbConnect();
try
{
connect.Open();
MessageBox.Show("Opened");
OleDbCommand command = new OleDbCommand();
command.Connection = connect;
command.CommandText = "Select * from Categories";
DataTable dt = new DataTable();
for (int i = 0; i < dt.Rows.Count; i++)
{
cmbDisplay.Items.Add(dt.Rows[i]["SeatNo"]);
}
}
catch (Exception ex)
{
MessageBox.Show("Exception in Database" + ex);
}
finally
{
connect.Close();
}
}
}

Your try block should resemble the following:
try
{
connect.Open();
MessageBox.Show("Opened");
OleDbCommand command = new OleDbCommand();
command.Connection = connect;
command.CommandText = "Select * from Categories";
DataTable dt = new DataTable();
//Put some data in the datatable!!
using(OleDbDataReader reader = command.ExecuteReader())
{
dt.Load(reader);
}
for (int i = 0; i < dt.Rows.Count; i++)
{
cmbDisplay.Items.Add(dt.Rows[i]["SeatNo"]);
}
}
You need to fill your DataTable with data!
You might also consider the following:
using(OleDbDataReader reader = command.ExecuteReader())
{
while(reader.Read())
{
cmbDisplay.Items.Add(reader.GetValue(reader.GetOrdinal("SeatNo"));
}
}
This way you don't even need to use a DataTable; this is a more efficient approach for large sets of data.
As an aside, you may wish to consider using Using:
using(OleDbConnection connect = db.dbConnect())
{
try
{
connect.Open();
//MessageBox.Show("Opened");
using(OleDbCommand command = new OleDbCommand())
{
command.Connection = connect;
command.CommandText = "SELECT * FROM Categories";
using(IDataReader reader = command.ExecuteReader())
{
while(reader.Read())
{
cmbDisplay.Items.Add(reader.GetValue(reader.GetOrdinal("SeatNo"));
}
}
}
}
catch (Exception ex)
{
MessageBox.Show("An erorr occured:" + ex);
}
}
This will ensure your connection, command and reader objects are disposed. This is not appropriate if you intend to hold onto an instance of your connection however as it will be closed AND disposed as soon as your code leaves the using statement.

There is missing filling DataTable dt with datas, which are returned by your sql command.

try with this code - in your sample you don't bind your table with data, you create new instance of table.
$ private void chkDetailsButton_Click(object sender, EventArgs e)
{
if (radioButtonA.Checked)
{
OleDbConnection connect = db.dbConnect();
try
{
connect.Open();
MessageBox.Show("Opened");
OleDbCommand command = new OleDbCommand();
command.Connection = connect;
command.CommandText = "Select * from Categories";
OleDbDataReader myReader = command.ExecuteReader();
while (myReader.Read())
{
cmbDisplay.Items.Add(myReader["SeatNo"]);
}
}
catch (Exception ex)
{
MessageBox.Show("Exception in Database" + ex);
}
finally
{
connect.Close();
}
}
}

I can't believe this. :D
When are you exactly filling the DataTable with data from DB?
There is nothing in between
DataTable dt = new DataTable();
and
for (int i = 0; i < dt.Rows.Count; i++)

you can fill combobox with Datatable :
SqlConnection con = new SqlConnection("Data Source=.;Initial Catalog=Test;Integrated Security=True");
SqlDataAdapter da = new SqlDataAdapter("select * from Books",con);
DataTable dt = new DataTable();
da.Fill(dt);
comboBox1.DisplayMember = "Name";
comboBox1.ValueMember = "ID";
comboBox1.DataSource = dt;

You are not filling data in Dataset before attaching try this
if(radio.checked)
{
try
{
connect.Open();
MessageBox.Show("Opened");
OleDbCommand command = new OleDbCommand();
command.Connection = connect;
command.CommandText = "Select * from Categories";
OleDbDataAdapter db = new OleDbDataAdapter();
DataSet ds = new DataSet();
db.SelectCommand = command;
db.Fill(ds);
for(int i=0;i<ds.Tables[0].Rows.Count;i++)
{
cmbDisplay.Items.Add(ds.Tables[0].Rows[i][0].ToString());
}
cmDisplay.DataBind();
}
catch (Exception ex)
{
MessageBox.Show("Exception in Database" + ex);
}
finally
{
connect.Close();
}
}