Develop Reference

Visual Studio Server Explorer show table data is blank

I am working on a Winforms c# program with a service-based database. I have created a table called Books which is empty and currently has no records.
Using some code, I am inserting into the table values. For some reason, when clicking Show Table Data, it still shows as blank despite me having added a record.
I checked to see if the record was there (but hidden) by using a DataGridView with the source of its data being the Books table. I could see the record had been created, but for some reason is not showing in the Server Explorer's Show Table Data view.
Here is my code for inserting a new record into the table:
string query = "INSERT INTO Books (ISBN, Title, Authors, Publishers, Genre, Page_Count, Quantity) VALUES (#isbn, #title, #authors, #publishers, #genre, #page_count, #quantity)";
string connectionString = "Data Source=(LocalDB)\\MSSQLLocalDB;AttachDbFilename=|DataDirectory|\\LMSDB.mdf;Integrated Security=True";
// Establish connection with database
using (SqlConnection connection = new SqlConnection(connectionString))
{
// Avoid SQL injection using parameters. Replace them with their real values
SqlCommand command = new SqlCommand(query, connection);
command.Parameters.AddWithValue("#isbn", isbn);
command.Parameters.AddWithValue("#title", title);
command.Parameters.AddWithValue("#authors", authors);
command.Parameters.AddWithValue("#publishers", publishers);
command.Parameters.AddWithValue("#genre", genre);
command.Parameters.AddWithValue("#page_count", pageCount);
command.Parameters.AddWithValue("#quantity", quantity);
try
{
connection.Open();
if (command.ExecuteNonQuery() == 1)
{
// 1 Row affected. Success
Console.WriteLine("Book added to database successfully");
ClearControlValues();
}
}
catch (Exception ex)
{
MessageBox.Show("An error occured:\n" + ex.Message);
}
finally
{
connection.Close();
}
}
As you can see, the Show Table Data view is appearing blank, despite me knowing that there is a record as I can see it on a DataGridView
Is there something I'm missing as to why the record isn't appearing?
EDIT: Solved thanks to Steve who pointed out that the Server Explorer and my code had different connection strings. Having changed these around, I now have the intended result.

I made a test with your code, and data can be inserted successfully.
As Steve said, the problem lies in your connection string.
And you can find your connectionstring by following steps:
1.Right-click on the connection name and select Properties.
2.There is an item called Connection String in the Properties window.
As follows:
Daniel Zhang

how to update data from table using C#.net

I've a form opened which is has loaded some sort of data (like username, CNIC, Contact no, etc etc) in Check boxes, now I want to update the data in such manner that I simply change the text in the text boxes and click on the save changes to save it. I've tried it but I am not able to do it in correct manner.
Let me show you how I've coded, the code I did in frmViewformList savechanges button is :
private void btnSaveChanges_Click(object sender, EventArgs e)
{
string sql;
string UserName;
UserName = txtUserName.Text; // saving data loaded on run time to UserName
sql = "";
sql += "UPDATE UserLogin";
sql += "SET Name = "+ //how to access data I've changed in TextBox after loading +"";
sql += "WHERE Name= " + //how to access data which was in text box right after loading + ""; //
}
I am a bit confused about how to refer to data, like the name already in the text box or the name which I have changed and how to write it in SQL query...
This question is a bit confusing, I know. Let me explain; the form is loaded, there are text boxes which is being populated with the data in database on load event, I change the data in text boxes and save on click so that the update query runs and changes the data in database as well.
I'm not able to create logic here how to do this, can any one help me out, I am sorry I am a new developer of C# that's why I am a bit confused.

You should use Sql Parameters in order to avoid SQL Injection which could leave your database vulnerable to malicious exploitation.
It's a good idea to separate the logic for performing the update to the logic where you create your query so you don't have to repeat code and so that you can maintain your code easier.
Here is an example you can reference:
public void DoWork()
{
// Build Query Use #Name Parameters instead of direct values to prevent SQL Injection
StringBuilder sql = new StringBuilder();
sql.Append("UPDATE UserLogin");
sql.Append("SET Name = #UpdatedName");
sql.Append("WHERE Name = #Name");
// Create parameters with the value you want to pass to SQL
SqlParameter name = new SqlParameter("#Name", "whatEverOldNameWas");
SqlParameter updatedName = new SqlParameter("#UpdatedName", txtUserName.Text);
Update(sql.ToString(), new [] { name, updatedName });
}
private static readonly string connectionString = "Your connection string"
private static readonly DbProviderFactory factory = DbProviderFactories.GetFactory("System.Data.SqlClient");
public static int Update(string sql, SqlParameter[] parameters)
{
try
{
using (DbConnection connection = factory.CreateConnection())
{
connection.ConnectionString = connectionString;
using (DbCommand command = factory.CreateCommand())
{
command.Connection = connection;
command.CommandText = sql;
foreach (var parameter in parameters)
{
if (parameter != null)
command.Parameters.Add(parameter);
}
connection.Open();
return command.ExecuteNonQuery();
}
}
}
catch (Exception)
{
throw;
}
}

You will want to strip all ', ", and ` characters out of your input so that people can't inject SQL. When you do SET Name = " +, you'll want to actually wrap whatever you're including in quotes because it's a string: SET Name = '" + UserName "' " +...
This is probably best done using
string.Format("UPDATE UserLogin SET Name = '{0}' WHERE Name = '{1}'", UserName, FormerUserName);
Then you will execute your query by using System.Data.SqlClient; and then work with SqlConnection to establish a connection to the server, and execute a SqlCommand of some kind; take a look at: http://www.codeproject.com/Articles/4416/Beginners-guide-to-accessing-SQL-Server-through-C

The following is a code snippet to insert data into database using ADO.NET and assuming SQL Server database.
At the top of your .cs file you should have.
using System.Data.SqlClient; // for sql server for other data bases you should use OleClient instead.
And inside your button click event you could put the following.
// to know how to get the right connection string please check this site: http://www.connectionstrings.com
string connString = "database connection string here";
using (SqlConnection con = new SqlConnection(connString))
{
con.Open();
//insert text into db
string sql_insert = "INSERT INTO ....."; // Use parameters here.
SqlCommand cmd_insert = new SqlCommand(sql_insert, con);
int rowsAffected = cmd_insert.ExecuteNonQuery();
}
Hopefully this is enough to get you started.

How to connect to Mysql using C#?

I'm just a beginner in C#. I'm using XAMPP server for MySQL database and Visual C# 2010. Then I have created a database named "testdb" in phpMyAdmin and a table named "login". I have inserted my username and password in the table. I'm doing a simple WinForm login where I made two text boxes for username and password and a button. I have my codes done and there's no compiler error. But I had troubled in one line. It says "Unable to connect to any of the specified MySQL hosts". I added MySql.Data to my references. I want to fetch the data in the database table when I'm going to log in. Then authorize the user or if not matched, it will prompt an error message.
Here is my code:
using MySql.Data.MySqlClient;
public bool Login(string username, string password)
{
MySqlConnection con = new MySqlConnection("host=localhost;username…");
MySqlCommand cmd = new MySqlCommand("SELECT * FROM login WHERE username='" +
username + "' AND password='" + password + "';");
cmd.Connection = con;
con.Open(); // This is the line producing the error.
MySqlDataReader reader = cmd.ExecuteReader();
if (reader.Read() != false)
{
if (reader.IsDBNull(0) == true)
{
cmd.Connection.Close();
reader.Dispose();
cmd.Dispose();
return false;
}
else
{
cmd.Connection.Close();
reader.Dispose();
cmd.Dispose();
return true;
}
}
else
{
return false;
}
}
*I hope for your your feedback. :)

Your immediate problem is probably either an incorrect connection string or the database server is not available. The connection string should be something like this
Server=localhost;Database=testdb;Uid=<username>;Pwd=<password>;
with <username> and <password> replaced with your actual values.
Besides that your code has several issues and you should definitely look into them if this is intended to become production code and probably even if this is just a toy project to learn something. The list is in particular order and may not be comprehensive.
Do not hard code your connection string. Instead move it to a configuration file.
Do not include plain text passwords in configuration files or source code. There are various solutions like windows authentication, certificates or passwords protected by the Windows Data Protection API.
Do not just dispose IDisposable instances by calling IDisposable.Dispose(). Instead use the using statement to release resources even in the case of exceptions.
Do not build SQL statements using string manipulation techniques. Instead use SqlParameter to prevent SQL injection attacks.
Do not store plain text passwords in a database. Instead at least store salted hashes of the passwords and use a slow hash function, not MD5 or a member of the SHA family.
You can use IDbCommand.ExecuteScalar to retrieve a scalar result and avoid using a data reader.
Comparing a boolean value with true or false is redundant and just adds noise to your code. Instead of if (reader.IsDBNull(0) == true) you can just use if (reader.IsDBNull(0)). The same holds for if (reader.Read() != false) what is equivalent to if (reader.Read() == true) and therefore also if (reader.Read()).
Using an O/R mapper like the Entity Framework is usually preferred over interacting with the database on the level of SQL commands.

Try modifying your ConnectionString accordingly to the Standard MySQL ConnectionString:
Server=myServerAddress;Database=myDataBase;Uid=myUsername;Pwd=myPassword;
Source:
MySQL ConnectionStrings
You can also take a look at the following link, that shows how to connect to a MySQL database using C#:
Creating a Connector/Net Connection String (MYSQL)

Make it simple and sql injection free, and also don't forget to add MySql.Web
in your references since your using XAMPP
public bool Login(string username, string password)
{
DataTable dt = new DataTable();
string config = "server=....";
using (var con = new MySqlConnection { ConnectionString = config })
{
using (var command = new MySqlCommand { Connection = con })
{
con.Open();
command.CommandText = #"SELECT * FROM login WHERE username=#username AND password=#password";
command.Parameters.AddWithValue("#username", username);
command.Parameters.AddWithValue("#password", password);
dt.Load(command.ExecuteReader());
if (dt.Rows.Count > 0)
return true;
else
return false;
} // Close and Dispose command
} // Close and Dispose connection
}

Stored procedure - INSERT query does not work

I'm writing a music player application using WPF (C#). As part of its functionality, I'm populating a music library, where I'm storing the Title and Path to an mp3 file. The user gets to select a root folder for his music library and then the contents are populated in a "Songs" table. This is the code that I've written:
private void Populate_Click(object sender, RoutedEventArgs e)
{
// Folder browser
FolderBrowserDialog dlg = new FolderBrowserDialog();
dlg.ShowDialog();
string DirectoryPath = System.IO.Path.GetDirectoryName(dlg.SelectedPath);
// Get the data directory
string[] A = Directory.GetFiles(DirectoryPath, "*.mp3", SearchOption.AllDirectories);
string[] fName = new string[A.Count()];
// Initialize connection
string connstr = "Data Source=.\\SQLEXPRESS;AttachDbFilename=|DataDirectory|\\Database.mdf;Integrated Security=True;User Instance=True";
SqlConnection conn = new SqlConnection(connstr);
conn.Open();
// Create the SqlCommand
SqlCommand cmd = new SqlCommand();
cmd.Connection = conn;
cmd.CommandType = CommandType.StoredProcedure;
cmd.CommandText = "InsertSongs";
// Create the parameters and execute the command
for (int i = 0; i < A.Count(); i++)
{
fName[i] = System.IO.Path.GetFileName(A[i]);
cmd.Parameters.AddWithValue("#Title", fName[i]);
cmd.Parameters.AddWithValue("#Path", A[i]);
try
{
cmd.ExecuteNonQuery();
}
catch (Exception ex)
{
System.Windows.MessageBox.Show("Error: " + ex.Message);
}
finally
{
listBox1.Items.Add(A[i]);
listBox2.Items.Add(fName[i]);
cmd.Parameters.Clear();
}
}
// Close the connection
cmd.Dispose();
conn.Close();
conn.Dispose();
}
The code for the stored procedure is simple -
ALTER PROCEDURE dbo.InsertSongs
(
#Title nvarchar(50),
#Path nvarchar(50)
)
AS
INSERT INTO Songs(Title, Path) VALUES(#Title, #Path)
Now, when I execute the program, there is no error message thrown (the file names and directory names have size less than 50). However, at the end of execution, no value is inserted in the Songs table.
The Songs table is described as below:
ID int
Title nvarchar(50)
Path nvarchar(50)
I'm not sure where I went wrong: I have also tried using SqlParameter and then defining the type of parameter as NVARCHAR with size 50, but to no avail. May I kindly request you to assist me here? Many thanks in advance.

The whole User Instance and AttachDbFileName= approach is flawed - at best! Visual Studio will be copying around the .mdf file and most likely, your INSERT works just fine - but you're just looking at the wrong .mdf file in the end!
If you want to stick with this approach, then try putting a breakpoint on the myConnection.Close() call - and then inspect the .mdf file with SQL Server Mgmt Studio Express - I'm almost certain your data is there.
The real solution in my opinion would be to
install SQL Server Express (and you've already done that anyway)
install SQL Server Management Studio Express
create your database in SSMS Express, give it a logical name (e.g. SongsDatabase)
connect to it using its logical database name (given when you create it on the server) - and don't mess around with physical database files and user instances. In that case, your connection string would be something like:
Data Source=.\\SQLEXPRESS;Database=SongsDatabase;Integrated Security=True
and everything else is exactly the same as before...

what is wrong in my code to call a stored procedure

I Have created a Stored procedure dbo.test as follows
use sample
go
create procedure dbo.test as
DECLARE #command as varchar(1000), #i int
SET #i = 0
WHILE #i < 5
BEGIN
Print 'I VALUE ' +CONVERT(varchar(20),#i)
SET #i = #i + 1
END
Now i am created a c# console application to call the stored procedure as follows
using System;
using System.Collections.Generic;
using System.Text;
using System.Data;
using System.Data.SqlClient;
namespace AutomationApp
{
class Program
{
public void RunStoredProc()
{
SqlConnection conn = null;
SqlDataReader rdr = null;
try
{
conn = new SqlConnection("Server=(TEST\\SQL2K5EXPRESS);DataBase=sample,IntegratedSecurity=SSPI");
conn.Open();
SqlCommand cmd = new SqlCommand("sample.dbo.test", conn);
cmd.CommandType = CommandType.StoredProcedure;
//cmd.ExecuteNonQuery();
rdr = cmd.ExecuteReader();
while (rdr.Read())
{
Console.WriteLine(String.Format("{0}, {1}",
rdr[0], rdr[1]));
}
}
catch(Exception ex)
{
Console.writeLine(ex.message);
}
finally
{
if (conn != null)
{
conn.Close();
}
if (rdr != null)
{
rdr.Close();
}
}
}
static void Main(string[] args)
{
Console.WriteLine("Hello World");
Program p= new Program();
p.RunStoredProc();
Console.Read();
}
}
}
O/P:
Hello World
//Could not find stored procedure 'test'.
A network-related or instance-specific error occurred while establishing a conne
ction to SQL Server. The server was not found or was not accessible. Verify that
the instance name is correct and that SQL Server is configured to allow remote
connections. (provider: SQL Network Interfaces, error: 26 - Error Locating Serve
r/Instance Specified)
But when i try to run the program it was closing so i debugged the program then at exactly at executeReader() method it was showed that can not find the stored procedure "dbo.test"
and when i give the "EXEC dbo.test" at SSMS it display the result as i expected.
waht is wronng with this any Help greatly Appreciated.

Why are you looking in the master database?
Also, your code needed some cleanup:
using System;
using System.Collections.Generic;
using System.Text;
using System.Data;
using System.Data.SqlClient;
namespace AutomationApp
{
class Program
{
public void RunStoredProc()
{
Console.WriteLine("\nTop 10 Most Expensive Products:\n");
using (SqlConnection conn =
new SqlConnection(
"Server=(local);DataBase=master;IntegratedSecurity=SSPI"))
{
conn.Open();
using (SqlCommand cmd =
new SqlCommand("dbo.test", conn) {
CommandType = CommandType.StoredProcedure})
{
using (SqlDataReader rdr = cmd.ExecuteReader())
{
while (rdr.Read())
{
Console.WriteLine(String.Format("{0}, {1}",
rdr[0], rdr[1]));
}
}
}
}
}
}
}

I would suggest it is related to teh permissions granted to the stored procedure.
Check out "GRANT EXECUTE <storedProc> TO <User>" you could also check the permissions in SSMS by right clicking on the stored proc.
I understand this is a test stored proc but it is not optimal to create stored procedures in the master database.
All the best :)

Just change your connection string:
conn = new SqlConnection("Server=(local);DataBase=master;IntegratedSecurity=SSPI");
You're hitting the master database. You want to hit whatever your database is called.
Alternatively, call the stored proc as dbname.dbo.test.

First of all - there's typo in your connection string - you need to use all semicolons - not semicolon once and commas the other time. Between DAtaBase= and IntegratedSEcurity, you have a comma - plus, it has to be "Integrated Security" (with a space!). Check out www.connectionstrings.com for the details on how to properly create a connection string.
Your original connection string in your post:
conn = new SqlConnection(
"Server=(TEST\\SQL2K5EXPRESS);DataBase=sample,IntegratedSecurity=SSPI");
should really be:
conn = new SqlConnection(
"Server=(TEST\\SQL2K5EXPRESS);DataBase=sample;Integrated Security=SSPI");
Once that would work, I think the main problem is that you're trying to pass in a SQL statement in the parameter #command to the stored procedure, which you execute inside the stored procedure (not in your current post, but in others you've posted), and you want to read out the rows returned by that statement.
But you have no way of being sure (short of parsing the SQL statement you're passing in) whether or not that SQL statement will actually indeed return values or whether it's a DDL statement like INSERT, CREATE TABLE or something.
So you have ADO.NET, calling a stored proc, which dynamically executes an arbitrary SQL statement, and you still want to be able to retrieve those results....
In my opinion, you need to rearchitect your approach - this will never work reliably - find another way to do what you're trying to do - there must be a way to do this with less dynamic execution of SQL inside a stored proc and stuff........ there's gotta be an easier way!
Marc

Have you tried just using "test" instead of "dbo.test"?

Your stored procedure doesn't return any results. Change your PRINT into SELECT.
You may be getting the error because ADO.NET doesn't know how to react to the status messages the print statement causes.

The SQL error you see is connecting to the server. It doesn't even get that far, so it isn't related to permissions at all. As far as your client goes, you'd get the same error if you connected to "Server=GroverCleveland\Instance1" (assuming it doesn't exist on your network).
I think that the problem is that you are wrapping the server name in parens, if you can connect to it fine using other SQL clients on the same client box. Try the following:
conn = new SqlConnection("Server=TEST\\SQL2K5EXPRESS;DataBase=sample;IntegratedSecurity=SSPI");
Marc is right about the semicolon, btw. Check out connectionstrings.com for details on that...