Develop Reference

How to display the proper data?

I have 2 datagridviews now i want to select a column named "Name" in the first datagridview and us it as the WHERE in my query to Select values from a table and put it in the other datagridview.
SqlCommand cmd = new SqlCommand();
cmd = ss.CreateCommand();
foreach (DataGridViewRow row in dgvAtt.Rows)
{
ss.Open();
cmd.CommandType = CommandType.Text;
string Query = "SELECT Signature FROM TBL_Student WHERE Name = '" +
row.Cells[4].Value.ToString() + "' ";
cmd.CommandText = Query;
cmd.ExecuteNonQuery();
DataTable dt = new DataTable();
SqlDataAdapter dp = new SqlDataAdapter(cmd);
dp.Fill(dt);
dgvSign.DataSource = dt;
ss.Close();
}
but it gives me error when there is null and it is only selecting the first row in the first datagridview.

You create in each foreach-loop a new DataTable and therefore it will always just have one Value. So you have to create it before the foreach-loop.
And make sure you check the Values you want to use before using them.
With this easy if-condition, there won't be any problems.
Edit1:
This code snippet is working just fine.
Just change the ConnectionString and you are done.
DataTable dt = new DataTable();
string error;
using (SqlConnection con = new SqlConnection(#"Data Source=SERVER;Initial Catalog=DATEBASE; User ID=USERNAME; Password=PASSWORD"))
{
SqlCommand cmd = new SqlCommand();
foreach (DataGridViewRow row in dgvAtt.Rows)
{
string Query = "SELECT Signature FROM TBL_Student WHERE Name = '";
if (row.Cells.Count >= 4 && row.Cells[4].Value != null)
{
Query += row.Cells[4].Value.ToString();
}
Query += "'";
try
{
cmd = new SqlCommand(Query, con);
if (con.State == ConnectionState.Closed)
con.Open();
SqlDataAdapter adapter = new SqlDataAdapter(cmd);
adapter.Fill(dt);
}
catch (Exception ex)
{
error = ex.Message;
}
}
}
dgvSign.DataSource = dt;

How to Use an Update Statement in SQLDataAdapter

I am trying to run an update statement after i built my sqldataadapter. I have column called INIT_PHASE in my table and if the INIT_PHASE is null or there is no data then i would like to set it to 1. I have tried but i can't seem to get it right the update statement. Pls. help. here is my code:
string ID = ddlPractice.SelectedValue;
string TYPE = DDL_TYPE.SelectedValue;
SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["myConnection"].ConnectionString);
SqlDataAdapter da = new SqlDataAdapter(#"select SET_SK, UNIT_NM, TYPE, INIT_PHASE FROM myTable WHERE UNIT_NM =#ID AND TYPE = #TYPE", con);
DataTable dtSETS = new DataTable();
da.SelectCommand.Parameters.AddWithValue("#ID", (ID));
da.SelectCommand.Parameters.AddWithValue("#TYPE", (TYPE));
da.Fill(dtSETS);
if (dtSETS.Rows.Count > 0)
{
DataRow dtSETS_row = dtSETS.Rows[0];
long SET_SK = dtSETS_row.Field<long>("SET_SK");
if (dtSETS_row.Field<string>("INIT_PHASE") == null)
{
//run update command here
update myTable set INIT_PHASE = 1;
}
}

One approach here would be to use the SqlCommandBuilder to build the UPDATE statement:
string ID = ddlPractice.SelectedValue;
string TYPE = DDL_TYPE.SelectedValue;
SqlConnection con = new SqlConnection(
ConfigurationManager.ConnectionStrings["myConnection"].ConnectionString);
SqlDataAdapter da = new SqlDataAdapter(
#"select SET_SK, UNIT_NM, TYPE, INIT_PHASE FROM myTable WHERE UNIT_NM =#ID AND TYPE = #TYPE",
con);
DataTable dtSETS = new DataTable();
da.SelectCommand.Parameters.AddWithValue("#ID", (ID));
da.SelectCommand.Parameters.AddWithValue("#TYPE", (TYPE));
da.Fill(dtSETS);
SqlCommandBuilder builder = new SqlCommandBuilder(da);
da.UpdateCommand = builder.GetUpdateCommand();
if (dtSETS.Rows.Count > 0)
{
DataRow dtSETS_row = dtSETS.Rows[0];
long SET_SK = dtSETS_row.Field<long>("SET_SK");
if (dtSETS_row.Field<string>("INIT_PHASE") == null)
{
dtSETS_row["INIT_PHASE"] = 1;
}
}
da.Update(dtSETS);
Take note to the following lines of code. Here we are building the update command:
SqlCommandBuilder builder = new SqlCommandBuilder(da);
da.UpdateCommand = builder.GetUpdateCommand();
here we are literally modifying the DataRow so that it's RowState is changed to Modified:
dtSETS_row["INIT_PHASE"] = 1;
and then finally, here we are sending updates to the database with the Update method on the SqlDataAdapter:
da.Update(dtSETS);
What this is going to do is only send updates for the rows with a RowState of Modified.
NOTE: each of the ADO.NET objects should be wrapped in a using. Refactor your code to match this type of template:
using (SqlConnection con = new SqlConnection(...))
{
using (SqlDataAdapter da = new SqlDataAdapter(...))
{
}
}

If I understand correctly, you could execute directly a command to update just this field
if (dtSETS_row.Field<string>("INIT_PHASE") == null)
{
SqlCommand cmd = new SqlCommand(#"UPDATE myTable set INIT_PHASE = 1 " +
"WHERE UNIT_NM =#ID AND TYPE = #TYPE", con);
cmd.Parameters.AddWithValue("#ID", (ID));
cmd.Parameters.AddWithValue("#TYPE", (TYPE));
cmd.ExecuteNonQuery();
}
You need to open the connection though both for the SqlDataAdapter and for the following command

You will have to use SqlCommandBuilder class for updating data in disconnected mode. ie) DataSet and Data Adapters.

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);

How to get data from SQL database to store in combo box - C#

How can i get the value of company_name from Comp table and store it on a comboBox?
here is my initial code on getting the values from Database and store it on a combobox:
string Sql = "select company_name from JO.dbo.Comp";
SqlConnection conn = new SqlConnection(connString);
SqlCommand cmd = new SqlCommand(Sql, conn);
cmd.CommandType = CommandType.StoredProcedure;
SqlDataAdapter da = new SqlDataAdapter(cmd);
DataSet ds = new DataSet();
da.Fill(ds);
for (int i = 0; i < ds.Tables[0].Rows.Count; i++)
comboBox1.Items.Add(ds.Tables[0].Rows[i][0].ToString());
it point out to da.fill(ds) and says "Could not locate entry in sysdatabases for database 'select company_name from JO'. No entry found with that name. Make sure that the name is entered correctly."
hope for your reply thanks!

Use datareader it is much simpler \
string Sql = "select company_name from JO.dbo.Comp";
SqlConnection conn = new SqlConnection(connString);
conn.Open();
SqlCommand cmd = new SqlCommand(Sql, conn);
SqlDataReader DR = cmd.ExecuteReader();
while (DR.Read())
{
combobox1.Items.Add(DR[0]);
}

If you set up your connection string to be something of this sort:
string SqlConnectionString = "Data Source=[SERVER];Initial Catalog=[DATABASE];"
Then using that set up, you can set your string 'Sql' as:
string Sql = "select company_name from dbo.Comp";
This could be a possible set up you could use to read out the values.
using (SqlConnection saConn = new SqlConnection(this.ConnectionString))
{
saConn.Open();
string query = "select DBName from dbo.Company";
SqlCommand cmd = new SqlCommand(query, saConn);
using (SqlDataReader saReader = cmd.ExecuteReader())
{
while (saReader.Read())
{
string name = saReader.GetString(0);
combobox1.Add(name);
}
}
saConn.Close();
}

I would like to introduce you a very simple way to SQL data into a combobox as:
first you have a create a SQL table,
in C# platform drop a combobox and go to its property,
in the property menu click on "DataSource"
specify the database and table to load into combobox,
Note, the combobox name and table's row should be the same.

{
SqlConnection con =new SqlConnection("Data Source=Server_Name;Initial Catalog=Database_Name;integrated security=true");
SqlCommand cmd;
SqlDataReader dr;
private void CashMemoForm_Load(object sender, EventArgs e)
{
con.Open();
cmd = new SqlCommand("Select Column_Name From Table_Name", con);
dr = cmd.ExecuteReader();
while (dr.Read())
{
comboBox1.Items.Add(dr[0]).ToString();
}
}
}

Have you ever tried Entity Framework for database access and dto creation?

Change your line to cmd.CommandType = CommandType.Text; instead of cmd.CommandType = CommandType.StoredProcedure;

Try this
string Sql = "select Company_ID,company_name from JO.dbo.Comp";
SqlConnection conn = new SqlConnection(connString);
SqlCommand cmd = new SqlCommand(Sql, conn);
cmd.CommandType = CommandType.Text;
SqlDataAdapter da = new SqlDataAdapter(cmd);
DataSet ds = new DataSet();
da.Fill(ds);
for (int i = 0; i < ds.Tables[0].Rows.Count; i++)
{
comboBox1.DataSource = ds.Tables[0];
comboBox1.DataTextField = "company_name";
comboBox1.DataValueField = "Company_ID";
comboBox1.DataBind();
comboBox1.Items.Insert(0, new ListItem("--Select--", "0"));
}

There is no use of for loop. you just need to check that whether the dataset contains rows or not.
string Sql = "select Company_ID,company_name from JO.dbo.Comp";
SqlConnection conn = new SqlConnection(connString);
SqlCommand cmd = new SqlCommand(Sql, conn);
cmd.CommandType = CommandType.Text;
SqlDataAdapter da = new SqlDataAdapter(cmd);
DataSet ds = new DataSet();
da.Fill(ds);
if (ds.Tables[0].Rows.Count > 0)
{
comboBox1.DataSource = ds.Tables[0];
comboBox1.DataTextField = "company_name";
comboBox1.DataValueField = "Company_ID";
comboBox1.DataBind();
comboBox1.Items.Insert(0, new ListItem("Select", "0"));
}

string Sql = "select company_name from JO.dbo.Comp";
SqlConnection conn = new SqlConnection(connString);
SqlCommand cmd = new SqlCommand(Sql, conn);
cmd.CommandType = CommandType.StoredProcedure;
SqlDataAdapter da = new SqlDataAdapter(cmd);
DataSet ds = new DataSet();
da.Fill(ds);
for (int i = 0; i < ds.Tables[0].Rows.Count; i++)
comboBox1.Items.Add(ds.Tables[0].Rows[i][0].ToString());

public System.Data.DataTable EmployeeViewAll()
{
DataTable dtbl = new DataTable();
try
{
// Here it shuld be your database Connection String
string connectionString = "Server = .; database = HKS; Integrated Security = true";
using (SqlConnection sqlCon = new System.Data.SqlClient.SqlConnection(connectionString))
{
SqlDataAdapter SqlDa = new SqlDataAdapter("employeeViewAll", sqlCon);
SqlDa.SelectCommand.CommandType = CommandType.StoredProcedure;
SqlDa.Fill(dtbl);
}
return dtbl;
}
catch (Exception)
{
throw;
}
}
public void ComboFill()
{
DataTable dt = new DataTable();
eSP SP = new eSP();
d = SP.EmployeeViewAll();
comboBox1.DataSource = dt;
comboBox1.DisplayMember = "department";
comboBox1.ValueMember = "empName";
}

How do i bind data source to a ComboBox?

So i currently have two combo boxes. One Being Manufacture the other being model. My sql query looks like this "Select Distinct Model From sheet1 where (Manufacture =#Manufacture)" this works when i execute it and if i were to fill a datagridtable. But if i try to place this into a combobox i get System.data.d...... etc for my selections. How can i just have it show the values instead of all this. What am i doing wrong?
private void ManuComboBox_SelectedIndexChanged(object sender, EventArgs e)
{
string manu = comboBox3.Text;
string conStr = "Data Source=CA-INVDEV\\RISEDB01;Initial Catalog=RISEDB01; Integrated Security=True";
string sqlcmd = "SELECT DISTINCT Model FROM Sheet1 WHERE (Manufacture =#Manufacture)";
using (SqlConnection conn = new SqlConnection(conStr))
{
SqlCommand cmd = new SqlCommand(sqlcmd, conn);
cmd.Parameters.AddWithValue("#Manufacture", manu);
SqlDataReader dr = cmd.ExecuteReader();
if (dr.HasRows)
{
dr.Close();
SqlDataAdapter dataAdapter = new SqlDataAdapter(cmd);
SqlCommandBuilder commandBuilder = new SqlCommandBuilder(dataAdapter);
DataTable table = new DataTable();
table.Locale = System.Globalization.CultureInfo.InvariantCulture;
dataAdapter.Fill(table);
bindingSource3.DataSource = table;
ModelComboBox.DataSource = bindingSource3;
}
}
}

Can you give this a try?
using (SqlConnection conn = new SqlConnection(conStr))
{
conn.Open();
SqlCommand cmd = new SqlCommand(sqlcmd, conn);
cmd.Parameters.AddWithValue("#Manufacture", manu);
SqlDataReader dr = cmd.ExecuteReader();
IList<string> modelList = new List<string>()
while (dr.Read())
{
modelList.add(dr[0].ToString());
}
ModelComboBox.DataSource = modelList;
}

If you have set the display member like:
ModelComboBox.DataSource = bindingSource3;
ModelComboBox.DisplayMember = "ColumnName";
And it still shows funny values, what are the values that it shows exactly?
Note, in a toolstrip it looks like you may have to also do:
ModelComboBox.BindingContext = this.BindingContext;
here is a reference

Try adding
ComboBox1.ItemsSource = bindingSource3
if this is your answer then mark it as answer