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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 )

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

What is C# equivalent of PHP's mysql_fetch_array function?

I am learning C#/ASP.NET and I am wondering what the C# equivalent of the following PHP code is?
I know the userid, and I want to fetch the rows from this table into the array of the variable "row", so I then can use it as "row['name']" and "row['email'].
$result = mysql_query("SELECT email, name FROM mytable WHERE id=7");
while ($row = mysql_fetch_array($result, MYSQL_ASSOC)) {
printf("Email: %s Name: %s", $row["email"], $row["name"]);
}
Thanks.

I'm not sure if this is the same as mysql_fetch_array but i assume that.
You can use IDBCommmand.ExecuteReader to create an IDataReader and use that to fill an Object[] with all fields of the row.
For example (using SQL-Server):
// use using statements to ensure that connections are disposed/closed (all implementing IDisposable)
using (var con = new SqlConnection(Properties.Settings.Default.ConnectionString))
using (var cmd = new SqlCommand("SELECT email, name FROM mytable WHERE id=#id", con))
{
cmd.Parameters.AddWithValue("#id", ID); // use parameters to avoid sql-injection
con.Open();
using (var reader = cmd.ExecuteReader())
{
while (reader.Read())
{
var fields = new object[reader.FieldCount];
// following fills an object[] with all fields of the current line,
// is this similar to mysql_fetch_array?
int count = reader.GetValues(fields);
}
}
}
Edit:
I don't mean to make it as similar as possible, but how would I go about getting the same end result (a variable with the results) in C#
That's a matter of taste. You could use some kind of ORM like Enity-Framework, NHibernate, LINQ-To-SQL or Stackoverflow's Micro-ORM Dapper.NET(what i'm using currently) or plain ADO.NET (as shown above).
You can use a custom class that you fill manually with a DataReader or a DataTable which schema is loaded automatically.
For example (here using MySQL):
DataTable tblEmail = new DataTable();
using (var con = new MySqlConnection(Properties.Settings.Default.MySQL))
using (var da = new MySqlDataAdapter("SELECT Email, Name FROM Email WHERE id=#id", con))
{
da.SelectCommand.Parameters.AddWithValue("#id", ID);
da.Fill(tblEmail);
}
if (tblEmail.Rows.Count == 1)
{
DataRow row = tblEmail.Rows[0];
String email = row.Field<String>("Email");
String name = row.Field<String>("Name");
}
As you can see, there are many ways in .NET. I have shown just two with ADO.NET.

There's no true equivalent. Having been a PHP developer in the past, I'd say the closest thing is to use a data adapter and fill a data table. Here's a reference to DbDataAdapter.Fill.
I'm not sure about the MySql driver but if you're using Sql Server here's some code to get you started:
using (var connection = new SqlConnection(connectionString))
{
var table = new DataTable("tbl_objects");
var adapter = new SqlDataAdapter();
adapter.SelectCommand = new SqlCommand("SELECT * FROM tbl_name", connection);
adapter.Fill(table);
}
Then, you can iterate over the rows in the table:
foreach(var row in table)
{
Console.WriteLine("{0}", row["ColumnName"]);
}

You could loop through your result with a foreach loop as follows:
foreach(var row in result)
{
console.writeline("Email:" + row.Email, "Name:", row.Name);
}
Is that the sort of thing you were looking for?
EDIT
In fact i have just seen you only have one result.
Then you can skip the foreach loop altogether

You need a connection to a database.
Assuming you are using mysql and an odbc connection.
var connectionString = "DRIVER={MySQL ODBC 3.51 Driver};" +
"SERVER=localhost;" +
"DATABASE=test;" +
"UID=venu;" +
"PASSWORD=venu;" +
"OPTION=3");
using (OdbcConnection connection = new OdbcConnection(connectionString))
{
OdbcCommand command = new OdbcCommand("SELECT email, name FROM mytable WHERE id=7", connection);
connection.Open();
// Execute the DataReader and access the data.
OdbcDataReader reader = command.ExecuteReader();
while (reader.Read())
{
//do stuff with the data here row by row the reader is a cursor
}
// Call Close when done reading.
reader.Close();
alternately you could use an odbcdataadapter and a datatable if you wanted all the results in a table you could use like an array.

The closest equivalent in .net would be something like this...
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using MySql.Data.MySqlClient;
namespace ConsoleApplication5
{
class Program
{
static void Main(string[] args)
{
var foo = MySqlHelper.ExecuteDataRow("Server=myServerAddress;Database=myDataBase;Uid=myUsername;Pwd=myPassword;", "select * from foo");
Console.WriteLine(foo["Column"]);
}
}
}
I assume you are using the MySql Data Connector http://dev.mysql.com/downloads/connector/net/
Do note there are better ways available in .net to connect to databases, but I think for a line by line, this is about as close to the PHP as you can get.

C# 'select count' sql command incorrectly returns zero rows from sql server

I'm trying to return the rowcount from a SQL Server table. Multiple sources on the 'net show the below as being a workable method, but it continues to return '0 rows'. When I use that query in management studio, it works fine and returns the rowcount correctly. I've tried it just with the simple table name as well as the fully qualified one that management studio tends to like.
using (SqlConnection cn = new SqlConnection())
{
cn.ConnectionString = sqlConnectionString;
cn.Open();
SqlCommand commandRowCount = new SqlCommand("SELECT COUNT(*) FROM [LBSExplorer].[dbo].[myTable]", cn);
countStart = System.Convert.ToInt32(commandRowCount.ExecuteScalar());
Console.WriteLine("Starting row count: " + countStart.ToString());
}
Any suggestions on what could be causing it?

Here's how I'd write it:
using (SqlConnection cn = new SqlConnection(sqlConnectionString))
{
cn.Open();
using (SqlCommand commandRowCount
= new SqlCommand("SELECT COUNT(*) FROM [LBSExplorer].[dbo].[myTable]", cn))
{
commandRowCount.CommandType = CommandType.Text;
var countStart = (Int32)commandRowCount.ExecuteScalar();
Console.WriteLine("Starting row count: " + countStart.ToString());
}
}

Set your CommandType to Text
command.CommandType = CommandType.Text
More Details from Damien_The_Unbeliever comment, regarding whether or not .NET defaults SqlCommandTypes to type Text.
If you pull apart the getter for CommandType on SqlCommand, you'll find that there's weird special casing going on, whereby if the value is currently 0, it lies and says that it's Text/1 instead (similarly, from a component/design perspective, the default value is listed as 1). But the actual internal value is left as 0.

You can use this better query:
SELECT OBJECT_NAME(OBJECT_ID) TableName, st.row_count
FROM sys.dm_db_partition_stats st
WHERE index_id < 2 AND OBJECT_NAME(OBJECT_ID)=N'YOUR_TABLE_NAME'