Develop Reference

c# display Access Database in DataGridView

First of all, here is my code:
private void Form5_Load(object sender, EventArgs e)
{
string strProvider = #"Provider = Microsoft.ACE.OLEDB.12.0; Data Source = c:\Users\name\Documents\myprogramms\example.accdb";
string strSql = "Select * from score";
OleDbConnection con = new OleDbConnection(strProvider);
OleDbCommand cmd = new OleDbCommand(strSql, con);
con.Open();
cmd.CommandType = CommandType.Text;
OleDbDataAdapter da = new OleDbDataAdapter(cmd);
DataTable scores = new DataTable();
da.Fill(scores);
data_example.DataSource = scores;
}
My goal is to display the data out of a MS Access Database. My codes has no error messages, but everytime I try to open the Data Grid View its completely empty.

your code snippet looks good. I cannot see any obvious issue.
Try to put breakpoint at the end of your method and check if datatable contains rows and rows contains any values in ItemArray.
Make sure your data_example DataGridView control is set AutoGenerateColumns = true (default) and check you have no other data source defined for your data_example DataGridView control. This code works for me.
private void Form1_Load(object sender, EventArgs e)
{
data_example.AutoGenerateColumns = true;
string strProvider = #"Provider = Microsoft.ACE.OLEDB.12.0; Data Source = c:\aaa\CinemaBooking.accdb";
string strSql = "Select * from Booking";
using (OleDbConnection con = new OleDbConnection(strProvider))
{
using (OleDbCommand cmd = new OleDbCommand(strSql, con))
{
using (OleDbDataAdapter da = new OleDbDataAdapter(cmd))
{
con.Open();
var scores = new DataTable();
da.Fill(scores);
data_example.DataSource = scores.DefaultView;
con.Close();
}
}
}
}
Maybe you can try to fill dataset with adapter and then use named table as datasource:
var dtSet = new DataSet();
da.Fill(dtSet, "Booking");
data_example.DataSource = dtSet.Tables["Booking"].DefaultView;

Combobox SelectedValue Returning System.Data.DataRowView even Converted to String

I am trying to change value of a TextBox control after the value of ComboBox changes. My code returns System.Data.DataRowView on the first time ComboBox value changes.
That is why I am getting an Object instead of the actual value on first call to my combobox.
private void radioButton2_CheckedChanged(object sender, EventArgs e)
{
SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["myconnectionString"].ConnectionString);
con.Open();
SqlDataAdapter da = new SqlDataAdapter();
SqlCommand cmd= new SqlCommand("SELECT donor_name,ID FROM donor_detail",con);
cmd.CommandType = CommandType.Text;
da.SelectCommand = cmd;
DataTable dt = new DataTable();
da.Fill(dt);
DonorName.DataSource = dt;
DonorName.DisplayMember = "donor_name";
DonorName.ValueMember = "ID";
con.Close();
}
And this is Event of change Value of ComboBox which is supposed to change value of my TextBox also when value in ComboBox changes.
private void DonorName_SelectionChangeCommitted(object sender, EventArgs e)
{
var id = Convert.ToString(DonorName.SelectedValue);
SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["myconnectionString"].ConnectionString);
con.Open();
String sql = "SELECT * from donor_detail WHERE ID=" + id + "";
SqlCommand cmd = new SqlCommand(sql,con);
SqlDataAdapter da = new SqlDataAdapter();
cmd.CommandType = CommandType.Text;
da.SelectCommand = cmd;
DataTable dt = new DataTable();
da.Fill(dt);
MessageBox.Show(sql);
mobile.Text = dt.Rows[0]["mobile"].ToString();
con.Close();
}

As mentioned here and several other places, this happens if you don't specify the datasource after the display and value members. This is the correct order:
DonorName.DisplayMember = "donor_name";
DonorName.ValueMember = "ID";
DonorName.DataSource = dt;

sql search query in c#

I'm trying to make a database search in my app where the user would choose the column and enter the search word and the result would come up in a dataviewgrid.
This is the code i've been working on, the problem is that nothing comes up and i'm pretty sure there are entries in the database. EDIT : it's a windows form application
private void button1_Click(object sender, EventArgs e)
{
conn = new SqlConnection("Server = localhost; database = Clients; Integrated Security = SSPI");
conn.Open();
SqlCommand cmd = new SqlCommand("SELECT * From dbo.Tclients WHERE #choice = #input", conn);
cmd.Parameters.AddWithValue("#choice", comboBox1.Text);
cmd.Parameters.AddWithValue("#input", textBox1.Text);
ds = new DataSet();
da = new SqlDataAdapter(cmd);
da.Fill(ds);
dataGridView1.DataSource = ds.Tables[0];
conn.Close();
}

You cannot use a parameter to express the name of a column.
You should populate your combobox with the column names and set its DropDownStyle property to DropDownList (do not allow your user to type the name of the column) and then build your query
private void button1_Click(object sender, EventArgs e)
{
string cmdText = "SELECT * From dbo.Tclients WHERE " + comboBox1.Text + " = #input";
using(SqlConnection conn = new SqlConnection(....))
using(SqlCommand cmd = new SqlCommand(cmdText, conn))
{
conn.Open();
cmd.Parameters.AddWithValue("#input", textBox1.Text);
ds = new DataSet();
da = new SqlDataAdapter(cmd);
da.Fill(ds);
dataGridView1.DataSource = ds.Tables[0];
}
}

you forgot to bind the grid view with datasource
add this after data source
dataGridView1.DataSource = ds.Tables[0];
dataGridView1.DataBind();

private void bunifuThinButton21_Click(object sender, EventArgs e)
{
SqlConnection connection = new SqlConnection();
connection.ConnectionString = (#"Data Source=.\SQLEXPRESS;AttachDbFilename=C:\Users\albasheer\Desktop\games\my_school\my_school\school.mdf;Integrated Security=True;User Instance=True");
connection.Open();
string sql = "select name,id,stage,age,cost from STUDENT where stage like '%" + bunifuCustomLabel1.Text + "%' and name like '%" + bunifuMaterialTextbox1.Text + "%'";
SqlDataAdapter adapter = new SqlDataAdapter(sql, connection);
SqlCommand command = new SqlCommand(sql, connection);
DataTable table = new DataTable();
adapter.Fill(table);
var dt = from t in table.AsEnumerable()
select new
{
id = t.Field<int>("id"),
Name = t.Field<string>("name"),
};
bunifuCustomDataGrid1.DataSource = dt.ToList();
}

Gridview in asp.net C#

I have two dropdownlist, corresponding to the values,gridview should be displayed,,and below is code for it..But i am not getting What's the problem in it!!
protected void ddlstudents_SelectedIndexChanged(object sender, EventArgs e)
{
if (ddlstudents.SelectedIndex > 0)
{
BindData();
}
}
private void BindData()
{
try
{
SQLiteConnection con = new SQLiteConnection("data source=C:\\ITS Database\\its.development.sqlite3");
string strquery = "select topics.name,course_coverages.progress from topics JOIN course_coverages on topics.id=course_coverages.topic_id where course_coverages.student_id=#studentid AND course_coverages.course_id=#courseid";
con.Open();
SQLiteCommand cmd = new SQLiteCommand();
cmd.connection=con;
cmd = con.CreateCommand();
cmd.CommandText = strquery;
cmd.Parameters.AddWithValue("#studentid", ddlstudents.SelectedIndex);
cmd.Parameters.AddWithValue("#courseid", ddlcourse.SelectedValue);
SQLiteDataAdapter ada = new SQLiteDataAdapter(cmd.CommandText, con);
SQLiteCommandBuilder cbl = new SQLiteCommandBuilder(ada);
DataTable dt = new DataTable();
ada.Fill(dt);
GridView1.DataSource = dt;
GridView1.DataBind();
con.Close();
}
catch (SQLiteException)
{
}
}
Any Help Would Be Appreciated!!
Thanks in Advance!!

Learn how to find the problem your self. if the gridview not showing correct data you can debug the application and find where it failed.
you have not given how you bind ddlstudents and ddlcourse , check the values you get for ddlstudents.SelectedIndex and ddlcourse.SelectedValue as you expected or not.
if values are correct, you can run the SQL statement on your database with above values and see the results.
If you really need to find the error, remove the try catch statement from your code,
If you catch the exception, do something with it. otherwise don't.

try this
protected void ddlstudents_SelectedIndexChanged(object sender, EventArgs e)
{
if (ddlstudents.SelectedIndex > 0)
{
BindData();
}
}
private void BindData()
{
try
{
SQLiteConnection con = new SQLiteConnection("data source=C:\\ITS Database\\its.development.sqlite3");
string strquery = "select topics.name,course_coverages.progress from topics JOIN course_coverages on topics.id=course_coverages.topic_id where course_coverages.student_id=#studentid AND course_coverages.course_id=#courseid";
con.Open();
SQLiteCommand cmd = new SQLiteCommand();
cmd.connection=con;
cmd = con.CreateCommand();
cmd.CommandText = strquery;
cmd.Parameters.AddWithValue("#studentid", ddlstudents.SelectedValue);
cmd.Parameters.AddWithValue("#courseid", ddlcourse.SelectedValue);
SQLiteDataAdapter ada = new SQLiteDataAdapter(cmd.CommandText, con);
SQLiteCommandBuilder cbl = new SQLiteCommandBuilder(ada);
DataTable dt = new DataTable();
ada.Fill(dt);
GridView1.DataSource = dt;
GridView1.DataBind();
con.Close();
}
catch (SQLiteException)
{
}
}

Populate a datagridview with sql query results

I'm trying to present query results, but I keep getting a blank data grid.
It's like the data itself is not visible
Here is my code:
private void Employee_Report_Load(object sender, EventArgs e)
{
string select = "SELECT * FROM tblEmployee";
Connection c = new Connection();
SqlDataAdapter dataAdapter = new SqlDataAdapter(select, c.con); //c.con is the connection string
SqlCommandBuilder commandBuilder = new SqlCommandBuilder(dataAdapter);
DataTable table = new DataTable();
table.Locale = System.Globalization.CultureInfo.InvariantCulture;
dataAdapter.Fill(table);
bindingSource1.DataSource = table;
dataGridView1.ReadOnly = true;
dataGridView1.DataSource = bindingSource1;
}
What's wrong with this code?

Here's your code fixed up. Next forget bindingsource
var select = "SELECT * FROM tblEmployee";
var c = new SqlConnection(yourConnectionString); // Your Connection String here
var dataAdapter = new SqlDataAdapter(select, c);
var commandBuilder = new SqlCommandBuilder(dataAdapter);
var ds = new DataSet();
dataAdapter.Fill(ds);
dataGridView1.ReadOnly = true;
dataGridView1.DataSource = ds.Tables[0];

String strConnection = Properties.Settings.Default.BooksConnectionString;
SqlConnection con = new SqlConnection(strConnection);
SqlCommand sqlCmd = new SqlCommand();
sqlCmd.Connection = con;
sqlCmd.CommandType = CommandType.Text;
sqlCmd.CommandText = "Select * from titles";
SqlDataAdapter sqlDataAdap = new SqlDataAdapter(sqlCmd);
DataTable dtRecord = new DataTable();
sqlDataAdap.Fill(dtRecord);
dataGridView1.DataSource = dtRecord;

You don't need bindingSource1
Just set dataGridView1.DataSource = table;

Try binding your DataGridView to the DefaultView of the DataTable:
dataGridView1.DataSource = table.DefaultView;

This is suppose to be the safest and error pron query :
public void Load_Data()
{
using (SqlConnection connection = new SqlConnection(DatabaseServices.connectionString)) //use your connection string here
{
var bindingSource = new BindingSource();
string fetachSlidesRecentSQL = "select top (50) * from dbo.slides order by created_date desc";
using (SqlDataAdapter dataAdapter = new SqlDataAdapter(fetachSlidesRecentSQL, connection))
{
try
{
SqlCommandBuilder commandBuilder = new SqlCommandBuilder(dataAdapter);
DataTable table = new DataTable();
dataAdapter.Fill(table);
bindingSource.DataSource = table;
recent_slides_grd_view.ReadOnly = true;
recent_slides_grd_view.DataSource = bindingSource;
}
catch (SqlException ex)
{
MessageBox.Show(ex.Message.ToString(), "ERROR Loading");
}
finally
{
connection.Close();
}
}
}
}

You may get a blank data grid if you set the data Source to a Dataset that you added to the form but is not being used. Set this to None if you are programatically setting your dataSource based on the above codes.

You may try this sample, and always check your Connection String, you can use this example with or with out bindingsource you can load the data to datagridview.
private void Employee_Report_Load(object sender, EventArgs e)
{
var table = new DataTable();
var connection = "ConnectionString";
using (var con = new SqlConnection { ConnectionString = connection })
{
using (var command = new SqlCommand { Connection = con })
{
if (con.State == ConnectionState.Open)
{
con.Close();
}
con.Open();
try
{
command.CommandText = #"SELECT * FROM tblEmployee";
table.Load(command.ExecuteReader());
bindingSource1.DataSource = table;
dataGridView1.ReadOnly = true;
dataGridView1.DataSource = bindingSource1;
}
catch(SqlException ex)
{
MessageBox.Show(ex.Message + " sql query error.");
}
}
}
}

you have to add the property Tables to the DataGridView Data Source
dataGridView1.DataSource = table.Tables[0];

if you are using mysql this code you can use.
string con = "SERVER=localhost; user id=root; password=; database=databasename";
private void loaddata()
{
MySqlConnection connect = new MySqlConnection(con);
connect.Open();
try
{
MySqlCommand cmd = connect.CreateCommand();
cmd.CommandText = "SELECT * FROM DATA1";
MySqlDataAdapter da = new MySqlDataAdapter(cmd);
DataTable dt = new DataTable();
da.Fill(dt);
datagrid.DataSource = dt;
}
catch(Exception ex)
{
MessageBox.Show(ex.Message);
}
}

Years late but here's the simplest for others in case.
String connectionString = #"Data Source=LOCALHOST;Initial Catalog=DB;Integrated Security=true";
SqlConnection cnn = new SqlConnection(connectionString);
SqlDataAdapter sda = new SqlDataAdapter("SELECT * FROM tblEmployee;", cnn);
DataTable data = new DataTable();
sda.Fill(data);
DataGridView1.DataSource = data;
Using DataSet is not necessary and DataTable should be good enough. SQLCommandBuilder is unnecessary either.

I think this professional way to Write from start, but you can use this code with MySQL bout I think they both are the same:
1/
using System.Data; AND using MySql.Data.MySqlClient;
2/
MySqlConnection con = new MySqlConnection("datasource=172.16.2.104;port=3306;server=localhost;database=DB_Name=root;password=DB_Password;sslmode=none;charset=utf8;");
MySqlCommand cmd = new MySqlCommand();
3/
public void SetCommand(string SQL)
{
cmd.Connection = con;
cmd.CommandText = SQL;
}
private void FillGrid()
{
SetCommand("SELECT * FROM `transport_db`ORDER BY `id` DESC LIMIT 15");
DataTable tbl = new DataTable();
tbl.Load(cmd.ExecuteReader());
dataGridView1.DataSource = tbl;
}

for oracle:
var connString = new ConfigurationBuilder().AddJsonFile("AppSettings.json").Build()["ConnectionString"];
OracleConnection connection = new OracleConnection();
connection.ConnectionString = connString;
connection.Open();
var dataAdapter = new OracleDataAdapter("SELECT * FROM TABLE", connection);
var dataSet = new DataSet();
dataAdapter.Fill(dataSet);