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Add SQL query on button using C#

I created a Windows Forms application in C# and my database in Visual Studio. I want to know how, if it's possible, to sort one of the columns in the table by clicking a button? Or how can I sort this column automatically without using a button?
I've tried to implement this sort in the code below, but it doesn't work :(
private c void button5_Click(object sender, EventArgs e)
{
SqlConnection sqlConnection = new SqlConnection("Here is my connecting string");
SqlCommand myCommand = new SqlCommand("SELECT * FROM [Information] ORDER BY (Перевозчик)", sqlConnection);
sqlConnection.Open();
myCommand.ExecuteNonQuery();
}

As found here: https://www.w3schools.com/sql/sql_orderby.asp
Sine we don't know what you want to oder we can only guess here.
But with the query you could try:
SELECT column1, column2, ...
FROM table_name
ORDER BY column1, column2, ... ASC
In your case:
"SELECT * FROM [Information] ORDER BY (Перевозчик) ASC"
Best would be to use the visual query builder where you can query against your database. When you are happy with your result you can at least be sure that the query is correct.
How you can do that is explained here:
https://www.c-sharpcorner.com/article/connect-to-a-database-from-visual-studio/
Since the sqlconnection and the sqlcommand is disposable you should consider putting it in a using tag, like in this example.
https://learn.microsoft.com/en-us/dotnet/api/system.data.sqlclient.sqlcommand?view=netframework-4.8
private static void ReadOrderData(string connectionString)
{
string queryString =
"SELECT OrderID, CustomerID FROM dbo.Orders;";
using (SqlConnection connection = new SqlConnection(
connectionString))
{
SqlCommand command = new SqlCommand(
queryString, connection);
connection.Open();
using(SqlDataReader reader = command.ExecuteReader())
{
while (reader.Read())
{
Console.WriteLine(String.Format("{0}, {1}",
reader[0], reader[1]));
}
}
}
}
There is 2 way for sort data
1) sorting just data and fill into grid:
DataGridView datagridview1 = new DataGridView(); // for show data
DataTable dt1 = new DataTable(); // have data
DataTable dt2 = new DataTable(); // temp data table
DataRow[] dra = dt1.Select("", "ID DESC");
if (dra.Length > 0)
dt2 = dra.CopyToDataTable();
datagridview1.DataSource = dt2;
2) sort default view that is like of sort with grid column header:
DataGridView datagridview1 = new DataGridView(); // for show data
DataTable dt1 = new DataTable(); // have data
dt1.DefaultView.Sort = "ID DESC";
datagridview1.DataSource = dt1;
I found this solution here:
Sorting rows in a data table
For a listbox you could give this a shot
ArrayList q = new ArrayList();
foreach (object o in listBox4.Items)
q.Add(o);
}
q.Sort();
listBox5.Items.Clear();
foreach(object o in q){
listBox5.Items.Add(o);
}
I found this solution here:
Sorting a list of items in a list box

You need to do ExecuteDatareader then process the result coming from this call. ExecuteNonQuery cannot be used to retrieve data.

C# reading values from datatable filled with sql select

I am coding win form app, which checks on startup right of the currently logged user. I had these right saved in MS SQL server in the table. When importing data to Datatable, there is no problem. But when I want to read value, there is message "cannot find column xy".
SqlDataAdapter sdaRights = new SqlDataAdapter("SELECT * FROM rights WHERE [user]='" + System.Security.Principal.WindowsIdentity.GetCurrent().Name + "'", conn);
DataTable dtRights = new DataTable(); //this is creating a virtual table
sdaRights.Fill(dtRights);
Object cellValue = dt.Rows[0][1];
int value = Convert.ToInt32(cellValue);
MessageBox.Show(value.ToString());
I would like, that program would save the value from SQL to int.

You are assuming that you have rows being returned, would be my first guess. You should loop through your DataTable instead of simply trying to access element 0 in it.
DataTable dtRights = new DataTable();
sdaRights.Fill(dtRights);
foreach(DataRow row in dtRights.Rows) {
Object cellValue = row[1];
int value = Convert.ToInt32(cellValue);
MessageBox.Show(value.ToString());
}

using (SqlConnection con = new SqlConnection("your connection string"))
{
using (SqlCommand cmd = new SqlCommand("SELECT [column_you_want] FROM [rights] WHERE [user] = #user"))
{
cmd.Parameters.AddWithValue("#user", System.Security.Principal.WindowsIdentity.GetCurrent().Name);
con.Open();
int right = Convert.ToInt32(cmd.ExecuteScalar());
}
}

Query giving only one result

My query is giving one result only i.e. one word for one URL when it should run for every entry in dt. Here dt is DataTable and contains many rows, url_given is a String. temp is table containing the words to be matched. Can anybody please tell me what is wrong with my query?
wordcount is the name of the table. url_String, word and count are columns.
The purpose of the query is to get the URLs matched with given URL and
their words which are in the list which is temp.
foreach (DataRow row in dt.Rows)
{
// read item
url_given = row["url_String"].ToString();
String qrystring = "select url_String,word,count from wordcount where url_String='" + url_given + "' and word in (select * from temp) ";
dt1 = db.searchandorder(qrystring);
// searchandorder is a call to a function that establishes the db connections and passes the query to the data adapter.
}
Here is my searchandorder function:
public DataTable searchandorder (String sql)
{
conn.Open();
SqlDataAdapter da = new SqlDataAdapter(sql, conn);
DataSet ds = new DataSet();
DataTable dt = new DataTable();
da.Fill( dt);
conn.Close();
Console.Write("table coloumns" + dt.Columns.ToString());
return dt;
}

Your problem comes from the fact you loop overwriting dt1 every time. You need to merge the results not replace them, but I can't say how you would do that without seeing db.searchandorder.
Also you have a very dangerous sql injection attack. If url_given was '; drop table wordcount; -- what would be the query the program will execute on the server? You need to use parameters with your data adapter.
EDIT: So, now that you shown your code, here is how you fix it. Instead of making a new DataTable every single time you pass you make one outside of the loop and pass in the same table every time. TableAdapter does not clear out the table before it fills by default.
private YourFunction(DataTable dt)
{
DataTable dt1 = new DataTable();
foreach (DataRow row in dt.Rows)
{
// read item
url_given = row["url_String"].ToString();
String qrystring = "select url_String,word,count from wordcount where url_String='" + url_given + "' and word in (select * from temp) ";
db.searchandorder(qrystring, dt1);
// searchandorder is a call to a function that establishes the db connections and passes the query to the data adapter.
}
DoSomthingWithResults(dt1);
}
public void searchandorder (String sql, DataTable dt)
{
conn.Open();
SqlDataAdapter da = new SqlDataAdapter(sql, conn);
da.Fill( dt);
conn.Close();
Console.Write("table coloumns" + dt.Columns.ToString());
return dt;
}
Now, that is the bare minimum to make your program work. There are a LOT of other bad practices you are doing.
Don't reuse a connection: Your conn object should be created inside searchandorder and be inside a using statement. Don't worry about making "too many connection", .NET will use connection pooling and reuse old connections.
Use using statments: Anything that implements IDisposable should be in a using statement (unless the item is being returned)
Follow naming standards: There is a set of standards C# code follows, your class searcandhorder should be named SerchAndOrder.
Use Parameters: You are vulnerable to a SQL injection attack use parameters for your data adapters. Not only does it improve safety, it makes your program faster by allowing SQL server to cache the query execution plan.
Here is a version of your program with those fixes applied.
private YourFunction(DataTable dt)
{
DataTable dt1 = new DataTable();
foreach (DataRow row in dt.Rows)
{
// read item
url_given = row["url_String"].ToString();
var parameter = new SqlParameter("#urlGiven", SqlDbType.VarChar, url_given.Length);
parameter.Value = url_given;
String qrystring = "select url_String,word,count from wordcount where url_String=#urlGiven and word in (select * from temp) ";
db.searchandorder(qrystring, dt1, parameter);
// searchandorder is a call to a function that establishes the db connections and passes the query to the data adapter.
}
DoSomthingWithResults(dt1);
}
public void SearchAndOrder (String sql, DataTable dt, params SqlParameter[] parameters)
{
using(var conn = new SqlConnection(_connectionString))
using(var da = new SqlDataAdapter(sql, conn))
{
da.SelectCommand.Parameters.AddRange(parameters);
conn.Open();
da.Fill(dt);
}
Console.Write("table coloumns" + dt.Columns.ToString());
return dt;
}

About fetching data from datatable to gridviewin c#

I am trying to get column names for particular data table.
I tried with this code.
datagridFieldCreation.AutoGenerateColumns = false;
DataTable dt = new DataTable();
SqlDataAdapter sda = new SqlDataAdapter("select * from Add_Information ", con);
sda.Fill(dt);
datagridFieldCreation.DataSource = dt;
I am getting full data that is there in table. But I want only column names to be displayed one by one. Can any one help me out??

You can use ExecuteReader(CommandBehavior.SchemaOnly)):
DataTable schema = null;
using (var con = new SqlConnection(connection))
{
using (var schemaCommand = new SqlCommand("SELECT * FROM Add_Information", con))
{
con.Open();
using (var reader = schemaCommand.ExecuteReader(CommandBehavior.SchemaOnly))
{
schema = reader.GetSchemaTable();
}
}
}
datagridFieldCreation.DataSource = schema;
SchemaOnly:
The query returns column information only. When using SchemaOnly, the
.NET Framework Data Provider for SQL Server precedes the statement
being executed with SET FMTONLY ON.
The column name is in the first column of every row.
foreach (DataRow col in schema.Rows)
{
Console.WriteLine("ColumnName={0}", col.Field<String>("ColumnName"));
}
Adpated from: Using GetSchemaTable() to retrieve only column names

You can use:
SELECT * FROM YOURTABLENAME WHERE 0=1

Yes for sure, it is simple query which has a conditional statement which is always returning false, so each time you execute the query no rows will be extracted and only columns you will get so you can easily put up these columns in you DataGridView.

Dataset to xml Null Values

I have the code below, where from 3 tables I take the data and write an xml.
I want write (when a record column has null value) the column on the xml with null value. For example if (Category_name == Null ) to write on the xml (Null) Right now the code skip the column and don’t even have this column on the xml.
string xmlFileData = "";
string[] tables = new string[] { "category", "company", "config" };
string query;
xmlFileData += "<MyXml>";
SqlConnection conn;
dbconnect obj;
obj = new dbconnect();//initailizing class object
for (int i = 0; i < tables.Length; i++)
{
string ifemptquery;
DataSet ds = new DataSet();
DataSet ds1 = new DataSet();
conn = obj.getConnection(); //calling connection function
ifemptquery = "SELECT * FROM " + tables[i] ";
SqlCommand cmd1 = new SqlCommand(ifemptquery, conn);
conn.Open();
SqlDataAdapter da1 = new SqlDataAdapter(cmd1);
DataTable dt1 = new DataTable();
da1.Fill(dt1);
conn.Close();
if (dt1.Rows.Count > 0)
{
query = "SELECT * FROM " + tables[i] ";
SqlCommand cmd = new SqlCommand(query, conn);
conn.Open();
SqlDataAdapter da = new SqlDataAdapter(cmd);
da.Fill(ds);
conn.Close();
conn.Dispose();
ds.DataSetName = tables[i];
string vartbname = tables[i];
string trimed_tbname = vartbname.Replace("_", "");
ds.Tables[0].TableName = trimed_tbname;
xmlFileData += ds.GetXml();
}
else
{
}
}
xmlFileData += "</MyXml>";
File.WriteAllText(Server.MapPath("~/xmlbackup/") + "Backup.xml", xmlFileData);

I have been searching the whole world for a solution of writing null fields to XML using DataSet.WriteXML(). The answer posted by Vlad is the one I also used in my project but I found that following works in a much more performance optimized way. I have created a function for your convenience. Change your dataset tables one after the other by calling the following function and replacing the tables.
private DataTable GetNullFilledDataTableForXML(DataTable dtSource)
{
// Create a target table with same structure as source and fields as strings
// We can change the column datatype as long as there is no data loaded
DataTable dtTarget = dtSource.Clone();
foreach (DataColumn col in dtTarget.Columns)
col.DataType = typeof(string);
// Start importing the source into target by ItemArray copying which
// is found to be reasonably fast for nulk operations. VS 2015 is reporting
// 500-525 milliseconds for loading 100,000 records x 10 columns
// after null conversion in every cell which may be usable in many
// circumstances.
// Machine config: i5 2nd Gen, 8 GB RAM, Windows 7 64bit, VS 2015 Update 1
int colCountInTarget = dtTarget.Columns.Count;
foreach (DataRow sourceRow in dtSource.Rows)
{
// Get a new row loaded with data from source row
DataRow targetRow = dtTarget.NewRow();
targetRow.ItemArray = sourceRow.ItemArray;
// Update DBNull.Values to empty string in the new (target) row
// We can safely assign empty string since the target table columns
// are all of string type
for (int ctr = 0; ctr < colCountInTarget; ctr++)
if (targetRow[ctr] == DBNull.Value)
targetRow[ctr] = String.Empty;
// Now add the null filled row to target datatable
dtTarget.Rows.Add(targetRow);
}
// Return the target datatable
return dtTarget;
}

Refer similar question here - dataSet.GetXml() doesn't return xml for null or blank columns
Apart from solutions mentioned there, you can also traverse through dataset and write XML using XmlTextWriter. This method is not recommended if you are dealing with huge data.