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Return SQL data to C# object

I am developing a website using ASP.NET C#. I have an SQL-Server database. I want to be able to retrieve data from the table with my data already in it.
For example, Here is my Details Table. I want to be able to do something like SELECT SteamName FROM Details WHERE SteamID = #SteamID and return the value that I get from the query to a C# object.
Here is the C# I have tried:
private void ReadSteamDetails()
{
using (SqlConnection connection = new SqlConnection(connectionString))
{
using (SqlCommand command = new SqlCommand())
{
command.Connection = connection;
command.CommandType = CommandType.Text;
command.CommandText = "SELECT SteamID FROM Details WHERE SteamID = #SteamID";
command.Parameters.Add("#SteamID", SqlDbType.NVarChar);
command.Parameters["#SteamID"].Value = SteamID;
connection.Open();
DisplaySQLID = command.ExecuteNonQuery().ToString();
connection.Close();
}
}
}
Running this code simply returns -1

You are using ExecuteNonQuery(), that returns an int value indicating the number of rows effected by the SQL statement. It should be used with insert, update or delete, but not with select statement.
When executing a select statement, you should use either ExecuteReader() if you want to iterate the query result using a DataReader, or use a DataAdapter to fill a DataSet or a DataTable, or use ExecuteScalar() if your query should return 0 or 1 results (and that's the case here).
Also, your code can and should be shorter - for instance, you can specify the select statement and connection object directly in the SqlCommand constructor.
Here is how I would write it:
using (SqlConnection connection = new SqlConnection(connectionString))
{
using (SqlCommand command = new SqlCommand("SELECT SteamID FROM Details WHERE SteamID = #SteamID", connection))
{
command.Parameters.Add("#SteamID", SqlDbType.NVarChar).Value = SteamID;
connection.Open();
DisplaySQLID = command.ExecuteSalar()?.ToString() ?? "";
}
}
Note that your query might not return any result so the ExecuteScalar() will return null, hence the use if the null conditional operator (?.) and the null coalescing operator (??).

For that exact query use ExecuteScalar instead of ExecuteNonQuery.

you can use the Entity Framework for that purpose. . .
with the combination of Entity Framework and link u can get your desire result set .
Entities entities = new Entities(Connection-String);
var result = entities.Details.Where(a=>a.SteamID = #SteamID )

Getting column information in SQL

I am somwhat new to SQL, so I am not sure I am going about this the right way.
I am trying to fetch data from my SQL Server database where I want to find out if checkedin is 1/0, but it needs to search on a specific user and sort after the newest date as well.
What I am trying to do is something like this:
string connectionString = ".....";
SqlConnection cnn = new SqlConnection(connectionString);
SqlCommand checkForInOrOut = new SqlCommand("SELECT CHECKEDIN from timereg ORDER BY TIME DESC LIMIT 1 WHERE UNILOGIN = '" + publiclasses.unilogin + "'", cnn);
So my question, am I doing this right? And how do I fetch the data collected, if everything was handled correctly it should return 1 or 0. Should I use some sort of SqlDataReader? I am doing this in C#/WPF
Thanks

using (SqlDataReader myReader = checkForInOrOut.ExecuteReader())
{
while (myReader.Read())
{
string value = myReader["COLUMN NAME"].ToString();
}
}
This is how you would read data from SQL, but i recommend you looking into Parameters.AddWithValue

There are some errors in your query. First WHERE goes before ORDER BY and LIMIT is an MySql keyword while you are using the Sql Server classes. So you should use TOP value instead.
int checkedIn = 0;
string cmdText = #"SELECT TOP 1 CHECKEDIN from timereg
WHERE UNILOGIN = #unilogin
ORDER BY TIME DESC";
string connectionString = ".....";
using(SqlConnection cnn = new SqlConnection(connectionString))
using(SqlCommand checkForInOrOut = new SqlCommand(cmdText, cnn))
{
cnn.Open();
checkForInOrOut.Parameters.Add("#unilogin", SqlDbType.NVarChar).Value = publiclasses.unilogin;
// You return just one row and one column,
// so the best method to use is ExecuteScalar
object result = checkForInOrOut.ExecuteScalar();
// ExecuteScalar returns null if there is no match for your where condition
if(result != null)
{
MessageBox.Show("Login OK");
// Now convert the result variable to the exact datatype
// expected for checkedin, here I suppose you want an integer
checkedIN = Convert.ToInt32(result);
.....
}
else
MessageBox.Show("Login Failed");
}
Note how I have replaced your string concatenation with a proper use of parameters to avoid parsing problems and sql injection hacks. Finally every disposable object (connection in particular) should go inside a using block

sqltransaction insert a double record while insert data

I am using that sqltransaction for the insert multiple tables each data.
But I have problem that have the database have the two same data.
What should I do for solve that problem?
please help me? Thanx
SqlConnection baglanti = system.baglan();
SqlCommand Trislem1_Ekle = new SqlCommand("Insert tblTr (Ad,TipID,BolgeID,Yerler,Resim) values(#Ad,#TipID,#BolgeID,#Yerler,#Resim) SELECT SCOPE_IDENTITY()", baglanti);
SqlCommand Tr2_TrAciklama = new SqlCommand("Insert tblTrAciklamaDetay (TrID,TrProgram) values((SELECT IDENT_CURRENT('tblTr')),#TrProgram)", baglanti);
Trislem1_Ekle.Parameters.AddWithValue("#Ad", txtTrAd.Text);
Trislem1_Ekle.Parameters.AddWithValue("#TipID", dlTrTip.SelectedValue);
Trislem1_Ekle.Parameters.AddWithValue("#BolgeID", BolgeID.SelectedValue);
Trislem1_Ekle.Parameters.AddWithValue("#Yerler", Yerler.Text);
Trislem1_Ekle.Parameters.AddWithValue("#Resim", Resim.SelectedValue);
Tr2_TrAciklama.Parameters.AddWithValue("#TrProgram", TrProgram.Text);
SqlTransaction sqlTrans = baglanti.BeginTransaction();
Trislem1_Ekle.Transaction = sqlTrans;
Tr2_TrAciklama.Transaction = sqlTrans;
try
{
Trislem1_Ekle.ExecuteNonQuery();
Tr2_TrAciklama.ExecuteNonQuery();
string SonIDGelen = Trislem1_Ekle.ExecuteScalar().ToString();
sqlTrans.Commit();
}
catch (Exception hata)
{
Response.Write("İşleminiz yapılamadı, Oluşan Hatanın Detayı<br />" + hata);
sqlTrans.Rollback();
}
finally
{
baglanti.Close();
baglanti.Dispose();
Trislem1_Ekle.Dispose();
Tr2_TrAciklama.Dispose();
}

As far as I see, you executing your Trislem1_Ekle command twice.
One with
Trislem1_Ekle.ExecuteNonQuery();
and the other one with;
string SonIDGelen = Trislem1_Ekle.ExecuteScalar().ToString();
Deleting the first one seems enough. Both ExecuteNonQuery and ExecuteScalar executes your query, and ExecuteScalar returns first column of the first row additionally.
Instead of disposing your database connections and commands manually, use using statement instead.
using(SqlConnection conn = new SqlConnection(conString))
{
using(SqlCommand cmd = conn.CreateCommand())
{
// Create your commands
// Add your parameter values
// Execute your commands
}
}
And don't use AddWithValue method. It may generate some unexptected results. Use .Add() method and overloads instead.
Can we stop using AddWithValue() already?

try like this
I think you are executing ExecuteScalar() twice on Command Trislem1_Ekle
Trislem1_Ekle.ExecuteNonQuery();
Tr2_TrAciklama.ExecuteNonQuery();
string SonIDGelen = Trislem1_Ekle.ExecuteScalar().ToString();
Replace with this:
string SonIDGelen = Trislem1_Ekle.ExecuteScalar().ToString();
Tr2_TrAciklama.ExecuteNonQuery();

Connecting to a Server

Trying to improve my C# to SQL skills... Currently I am using this bit of code to pull data from our application server. I have two different DBA's telling me two other ways to write this, just trying to figure out if this should be improved on or changed. If so, I would really appreciate some kind of examples.
FYI: This code...
db.con(user.Authority)
...Is essentially a 'new sqlconnection' code.
DataTable dtInfo = new DataTable("SomeInfo");
using (SqlConnection con = db.con(user.Authority))
{
string command = "SOME SQL STATEMENT;";
using (SqlCommand cmd = new SqlCommand(command,con))
{
cmd.CommandType = CommandType.Text;
cmd.Parameters.AddWithValue("#Param", sqlDbType).Value = Param;
con.Open();
cmd.ExecuteNonQuery();
**********
*** OR ***
**********
cmd.CommandType = CommandType.Text;
cmd.Parameters.AddWithValue("#Param", sqlDbType).Value = Param;
using (SqlDataAdapter da = new SqlDataAdapter(cmd))
{
da.Fill(dtInfo );
}
}
}
So, if I'm understanding the provided information, this is my best route?
using (SqlConnection con = db.con(user.Authority))
{
string command = "SELECT [TBL_EMPLOYEE].[ACTIVE_DIRECTORY] FROM [TBL_EMPLOYEE];";
using (SqlCommand cmd = new SqlCommand(command, con))
{
con.Open();
using (SqlDataReader reader = cmd.ExecuteReader())
{
while (reader.Read())
{
MessageBox.Show(reader["ACTIVE_DIRECTORY"].ToString());
}
}
}
And one last thing... This should prevent the need for
cmd.Dispose();
etc...

The code would depend on the specific query. If the query retrieves rows of data (as a SELECT does), then you would go the da.Fill() route. If it's a query that just makes a change to the database (such as INSERT, UPDATE, or DELETE), then you would use ExecuteNonQuery().

I would not use the SqlDataAdapter version. The version that uses the SqlCommand object and the SqlDataReader will perform better, and allows more insight into the actual data being returned.
// Assumes the following sql:
// SELECT foo, bar FROM baz
// error checking left out for simplicity
var list = new List<SomeClass>();
using(var reader = cmd.ExecuteReader()) {
while(reader.Read()) {
list.Add(new SomeClass {
// NOTE: you can see the columns that the c# is referencing
// and compare them to the sql statement being executed
Foo = (string)reader["foo"],
Bar = (string)reader["bar"]
});
}
}
Later as your level of experiance increases you will be able to use other features of the SqlCommand and SqlDataReader classes in order to ensure that the code executes as quickly as possible. If you start using the SqlDataAdapter route, you will eventually have to relearn how to do the exact same things you have already been doing because the SqlCommand and SqlDataReader have operations that do not exist elsewhere in .NET.

ExecuteNonQuery returns the number of rows effected.
A DataTable is not an efficient way to retrieve that number.
int rowsRet = cmd.ExecuteNonQuery();
SqlCommand.ExecuteNonQuery Method

How can I insert/update rows with C# to SQL Server

I am quit busy turning a old classic asp website to a .NET site. also i am now using SQL Server.
Now I have some old code
strsql = "select * FROM tabel WHERE ID = " & strID & " AND userid = " & struserid
rs1.open strsql, strCon, 2, 3
if rs1.eof THEN
rs1.addnew
end if
if straantal <> 0 THEN
rs1("userid") = struserid
rs1("verlangid") = strID
rs1("aantal") = straantal
end if
rs1.update
rs1.close
I want to use this in SQL Server. The update way. How can I do this?
How can I check if the datareader is EOF/EOL
How can I insert a row id it is EOF/EOL
How can I update a row or delete a row with one function?

If you want to use raw SQL commands you can try something like this
using (SqlConnection cnn = new SqlConnection(_connectionString))
using (SqlCommand cmd = new SqlCommand())
{
cnn.Open();
cmd.Connection = cnn;
// Example of reading with SqlDataReader
cmd.CommandText = "select sql query here";
using (SqlDataReader reader = cmd.ExecuteReader())
{
while (reader.Read())
{
myList.Add((int)reader[0]);
}
}
// Example of updating row
cmd.CommandText = "update sql query here";
cmd.ExecuteNonQuery();
}

It depends on the method you use... Are you going to use Entity Framework and LINQ? Are you going to use a straight SQL Connection? I would highly recommend going down the EF route but a simple straight SQL snippet would look something like:
using (var connection = new SqlConnection("Your connection string here"))
{
connection.Open();
using (var command = new SqlCommand("SELECT * FROM xyz ETC", connection))
{
// Process results
using (SqlDataReader reader = command.ExecuteReader())
{
while (reader.Read())
{
int userId = (int)reader["UserID"];
string somethingElse = (string)reader["AnotherField"];
// Etc, etc...
}
}
}
// To execute a query (INSERT, UPDATE, DELETE etc)
using (var commandExec = new SqlCommand("DELETE * FROM xyz ETC", connection))
{
commandExec.ExecuteNonQuery();
}
}
You will note the various elements wrapped in using, that is because you need to release the memory / connection when you have finished. This should answer your question quickly but as others have suggested (including me) I would investigate Entity Framework as it is much more powerful but has a learning curve attached to it!

You can use SQL store procedure for Update. And call this store procedure through C#.
Create procedure [dbo].[xyz_Update]
(
#para1
#para2
)
AS
BEGIN
Update tablename
Set Fieldname1=#para1,
Set Feildname2=#para2
end