I'm recently new at C# and follow a tutorial on connection to the database, the connection for viewing or SELECT command was ok, I made some revision based on the threads of forums to make my code better, but when I was in INSERT for my SQL Server, I have some problems. I was able to insert the data but when I re-run the program the data that I just inserted earlier was not in the database.
Here is my code on insert
string commandText = "INSERT INTO loginInfo (name, pass, role) VALUES(#name, #pass, #role)";
using (connection = new SqlConnection(connectionString))
{
SqlCommand command = new SqlCommand(commandText, connection);
command.CommandType = CommandType.Text;
command.Parameters.AddWithValue("#name", textBox1.Text);
command.Parameters.AddWithValue("#pass", textBox2.Text);
command.Parameters.AddWithValue("#role", textBox3.Text);
try
{
command.Connection.Open();
command.ExecuteNonQuery();
}
catch
{
}
finally
{
command.Connection.Close();
}
}
I'm trying to create a simple CRUD but not save the data... please help
If you're using the AttachDbFileName= clause in your connection string, you might have fallen victim to a well-known issue : you might just be looking at the wrong database (file) when checking your data.
When running your app in Visual Studio, it will be copying around the .mdf file (from your App_Data directory to the output directory - typically .\bin\debug - where you app runs) 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 connection.Close() call - and then inspect the .mdf file with SQL Server Mgmt Studio Express - I'm almost certain your data is there.
The long-term viable 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. YourDatabase)
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=YourDatabase;Integrated Security=True
and everything else is exactly the same as before...
Also see Aaron Bertrand's excellent blog post Bad habits to kick: using AttachDbFileName for more background info.
Related
I'm trying to copy all the data from my datatable into my database.
I'm using Microsoft SQL Server Database File as my database.
Here's the code I'm using,
private void button1_Click(object sender, EventArgs e)
{
connection.ConnectionString = connectionString;
connection.Open();
DataTable dt1 = new DataTable();
dt1 = ((DataTable)dataGridView1.DataSource).Copy();
SqlTransaction transaction = connection.BeginTransaction();
using (SqlBulkCopy bulkCopy = new SqlBulkCopy(connection,
SqlBulkCopyOptions.TableLock |
SqlBulkCopyOptions.FireTriggers,
transaction))
{
bulkCopy.DestinationTableName =
"dbo.StudentInfIns";
try
{
bulkCopy.WriteToServer(dt1);
transaction.Commit();
connection.Close();
}
catch (Exception ex)
{
Console.WriteLine(ex.ToString());
}
}
}
Any idea as to why it won't go through?
The whole AttachDbFileName= approach is flawed - at best! When running your app in Visual Studio, it will be copying around the .mdf file (from your App_Data directory to the output directory - typically .\bin\debug - where you app runs) 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 transaction.Commit(); 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. MainDB)
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=MainDB;Integrated Security=True
and everything else is exactly the same as before...
Also see Aaron Bertrand's excellent blog post Bad habits to kick: using AttachDbFileName for more background info.
I'm trying to write a C# application that restores many databases from .bak files placed in a certain folder. To do so I need the databases logical name from the files.
So I want to execute the following query :
RESTORE FILELISTONLY FROM DISK = N'C:\Folder\File'
The problem is: I can't get the result of this to my application, when I execute it in SQL Server Management Studio, it shows the name I want.
I tried to use ExecuteReader function from SqlDataReader but it doesn't return any data.
Can someone help me figure out how to get the result of queries like restore database, backup database into a variable in a C# application ?
Thanks in advance
The command RESTORE FILELISTONLY does return a result set as per the documentation RESTORE Statement - FILELISTONLY. What I did find during testing my code, you need to make sure the user that is running the application has permissions to read the specified file and directory. Otherwise you will run into issues.
For a code example of this:
var command = #"RESTORE FILELISTONLY FROM DISK = N'F:\Microsoft SQL Server\MSSQL13.MSSQLSERVER\MSSQL\Backup\Scratch.bak'";
using (var sqlConnection = new SqlConnection("Server=localhost;Database=Scratch;Trusted_Connection=True;"))
using (var sqlCommand = new SqlCommand(command, sqlConnection))
{
sqlConnection.Open();
var sqlDataReader = sqlCommand.ExecuteReader();
while (sqlDataReader.Read())
{
Console.WriteLine($"Logical Name: {sqlDataReader["LogicalName"]}");
Console.WriteLine($"Physical Name: {sqlDataReader["PhysicalName"]}");
Console.WriteLine($"Type: {sqlDataReader["Type"]}");
}
}
You may also find that when trying to work SQL Server management, using the SqlConnection and SqlCommand objects may be more frustrating then they are worth. I strong recommend using the SQL Server Management Objects (SMO). This is actually what management studio uses when you are work with SQL Server. I have an example on GitHub if you are interested in it. Checkout GitHub: SMO Demo.
I have a problem I need to solve, but not know how exactly. I have a WinForms application (C#) which connects to an online MySQL server - no problem there. In this application I have an option to make database backups (basically I dump this database to a local file on a computer).
I would like to locally "open" this backup on client's computer (to check some old data) - I don't want to make database restore on my server, because database must still be in use for other users. I want to make clean install of MySQL on a local computer and connect to it trough localhost (like I do for testing ), but I do not have physical access to that computer. I can send MySQL installer to my client, but how to go about automatically creating user with password and database from my dump file?
I know how to create a new database if it doesn't exist, but how to do it if it's clean install of MySQL server - no user and password yet.
string connStr = "server=localhost;user=root;port=3306;password=????;";
using (var conn = new MySqlConnection(connStr))
using (var cmd = conn.CreateCommand())
{
conn.Open();
cmd.CommandText = "CREATE DATABASE IF NOT EXISTS `hello`;";
cmd.ExecuteNonQuery();
}
Any help and direction is appreciated.
Regards!
I don't know whether I understand your problem. However,if you install a new Mysql，you can use root user through no database.
Anyway, one thing you need to know,Connect database must has user and password for mysql or sqlserver.
You may need to be more concise description of your problem.
I am completely new sql/database applications and am trying out a simple contact management applicaton using Visual Studio 2015 C#. I am using 'SQL Express LocalDB'. I have read on google that it is meant for development purpose, but microsoft also mentions that it could be used for production purpose too.
My problem is that when I try out the application from my developement system, the application first time takes few seconds to load but after that every query runs quickly. When I tried this on one my friends system, it takes time everytime I try to use any query. The database is just with 20-30 records.
I create new connection using 'new SqlConnection' and then execute command created by 'new SqlCommand' and after executing query I close the connection.
Here is the code snippet from my app
SqlConnection sqlConnection = new SqlConnection(#"Data Source = (LocalDB)\MSSQLLocalDB; AttachDbFilename = ""C:\ContactsDB.mdf""; Integrated Security = True; Connect Timeout = 30";);
SqlCommand sqlCmd = new SqlCommand();
sqlCmd.Connection = sqlConnection;
sqlCmd.CommandText = "SELECT Id, first_name, last_name from ContactsMaster ORDER BY first_name";
sqlConnection.Open();
SqlDataReader reader = sqlCmd.ExecuteReader();
try
{
while (reader.Read())
{
ListViewItem lvi = new ListViewItem(reader["first_name"]);
listViewItems.Add(lvi);
lvi.SubItems.Add(reader[0].ToString());
}
}
finally
{
reader.Close();
}
sqlConnection.Close();
Q. Should I keep the connection open all the time while app is running? I don't think this should be suggested. As if app crashes database can get corrupt.
One of the backdrop which ppl saying that LocalDB closes the connection every new milliseconds. So should I keep pinging the database every few milliseconds? Or I should not use localdb in production at all?
I want to make the app such that the requirement goes really low regaridng the database prerequisites. Like LocalDB installation is really seamless.
I have not used SQL Server Express, does Express installation is also seamless like LocalDB and can I use the connection string like LocalDB in Express too, giving the .mdf filename directly?
localdb has auto shutdown. default is 5 min. you can set it to higher value (ie: 12hour).
max is 65535 min.
see: How to prevent SQL Server LocalDB auto shutdown?
also sqlexpress autoshutdown is 1hour if im not wrong.
symptoms on my pc:
first open is 10- 30 seconds slow. if i reopen app right after it is below 1 second. if i wait for a while it is slow again
There are many things to take in count for ddbb performance, it's not a simple question. For such small amount of records there shouldn't be performance problems. Try storing the ddbb files in another disk different from OS disk, and even better, place data file and log file in different disks too.
About your question, connections must be always closed and disposed properly in a finally block or inside a using block.
Sql Express is very easy to install, and also use a connection string, been the biggest difference that it can be used across the network.
Finally moved to SQLite and that is much faster in compare to SQLLocalDB.
I need your help.. maybe it's the small task which I am not able to solve but I don't know how to search that on any search engine
I am using an .mdf file (vs 2103) in my WPF login register desktop application.. Everything is working fine, no compilation errors. I inserted some data into the .mdf file by using query in Visual Studio and then try to login through application and it's working fine. Moreover I am also able to register, i.e., insert into .mdf file from the register option of application if I use the "absolute path" of the .mdf file. Problem begins when I try to insert into .mdf file using a "relative path"... it doesn't insert data into the .mdf....I don't know why.
(this absolute path is not working. I have .mdf file in the database folder)
//connection string
connetionString = #"Data Source=(LocalDB)\v11.0;AttachDbFilename=|DataDirectory|\Database\Database1.mdf;Integrated Security=True";
//code
SqlCommand sqlCmd;
string sql = null;
SqlConnection sqlCnn = new SqlConnection(connetionString);
try
{
sqlCnn.Open();
sql = "insert into [NewTable] ( Name , Password ) values ('ABC' , '12345')";
sqlCmd = new SqlCommand(sql, sqlCnn);
sqlCmd.ExecuteNonQuery();
sqlCnn.Close();
MessageBox.Show("You have Been Registered");
}
catch (Exception ex)
{
MessageBox.Show("" + ex);
}
It shows the message "You have Been Registered"
but is not visible in .mdf file...
I want to ask..why is it behaving like this....and I want to use the relative path as we cant judge the client system absolute path...what mistake I am doing? how to handle this (i guess self made) issue?
The whole AttachDbFileName= approach is flawed - at best! When running your app in Visual Studio, it will be copying around the .mdf file (from your App_Data directory to the output directory - typically .\bin\debug - where you app runs) 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. MyDatabase)
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=MyDatabase;Integrated Security=True
and everything else is exactly the same as before...
Also see Aaron Bertrand excellent blog article Bad habits to kick: Using AttachDbFileName for more in depth explanations and tips