I'm having some trouble getting my Entity Framework connection strings working from my main application and from my class library. Both my main application (an *.exe) and my class library (a COM *.dll that I want to use with Excel) will need to create a connection to either a SQL Server CE database or a SQL Server database.
At the moment, I define two 'base' connection strings in the config file, one for the SQL Server CE implementation and one for the SQL Server implementation. This works fine for my main application, as it reads the appropriate 'base' connection string from the config file (either SQL Server CE or SQL Server), I adjust the connection string value (e.g. file location via 'data source=' for SQL Server CE or database name for SQL Server), and I'm good to go. This however doesn't work well for my class library, as the config file depends on the application that is using the library. I'd like to therefore get rid of my config file dependency completely, by defining my connection strings in code as opposed to in the config file.
The current config file configuration looks as follows:
<add name="ConnectionCE" providerName="System.Data.SqlServerCe.4.0" connectionString="" />
<add name="ConnectionServer" providerName="System.Data.SqlClient" connectionString="" />
I then create the context as follows:
var context = new DbContext("name=ConnectionCE")
//Do things with the context above here, e.g. change the connection string value.
How can I convert the "ConnectionCE" and "ConnectionServer" connection strings so that I don't have to rely on the config file, and can create these directly in my C# code (with the correct provider)?
Thanks!
DbContext(string) constructor accepts name or connection string.
You can simply build the connection string in code and pass it into the constructor.
You can use System.Data.SqlClient.SqlConnectionStringBuilder class to build connection string for SQL Server. I think, for SQL Server CE connection string, it is easy to use string.Format().
The code for SQL Server will look like:
var connStr = new SqlConnectionStringBuilder
{
InitialCatalog = "YourDb",
IntegratedSecurity = true,
DataSource = #".\SQLServer",
};
var db = new DbContext(connStr.ConnectionString);
Provider should be specified for SQL Server CE, so the code will look like next:
var conn = DbProviderFactories.GetFactory("System.Data.SqlServerCe.4.0").CreateConnection();
conn.ConnectionString = "DataSource = \"C:\\ExistingDBFile.db\"";
var db = new DbContext(conn, true);
Related
I just created a desktop Winforms application with localhost database.
The connect string I am using is this:
SqlConnection connect = new SqlConnection(#"Data Source=(LocalDB)\MSSQLLocalDB;AttachDbFilename=C:\Users\Administrator\Desktop\learningsystem\LearningSystem\LearningSystem\LearningSystem.mdf;Integrated Security=True");
If I want to run my application on other computers, how should I make it work?
EDIT：SOLUTION
Thank for all the help! I tried the following steps. I think it is working now. But please correct me if I did something tricky.
1. add a new setting item in project property setting. App.config will automatically update:
<connectionStrings>
<add name="LearningSystem.Properties.Settings.LearningConn" connectionString="Data Source=(LocalDB)\MSSQLLocalDB;AttachDbFilename=|DataDirectory|\LearningSystem.mdf;Integrated Security=True;Connect Timeout=30"
providerName="System.Data.SqlClient" />
</connectionStrings>
2. In my program, just add the following statement to connect to the sql server
SqlConnection connect = new SqlConnection(#"Data Source = (LocalDB)\MSSQLLocalDB; AttachDbFilename=|DataDirectory|\LearningSystem.mdf;Integrated Security = True; Connect Timeout = 30");
Further question
If others will run this application on their computer(not in the same network), they just go into the project setting and change the value by selecting the database file I provide to them,the connectionString will automatically change, right?
Thanks!
It's generally a bad idea to hard code such stuff in your application. Normally, application settings and connection strings are placed in the application's configuration file (in the ConnectionStrings section).
Just like with all strings, you could build your connectionstring from dynamic parts (variables, settings, etc.) and then pass that generated connectionstring to the SqlConnection constructor. Again, to make those separate parts configurable without hard coding them in your application, you might want to add them to your application's configuration file (in the AppSettings section). But IMHO this is an overly complex solution in most scenarios. Putting the entire connectionstring in the ConnectionStrings section is more straightforward (and more flexible).
Anyway, again, to make your application configurable, you might use your application's configuration file (App.config or Web.config), you need to add a reference to System.Configuration in your project's .NET Framework dependencies and use the AppSettings and ConnectionStrings properties of the System.Configuration.ConfigurationManager class.
(Of course, there are more ways to make your application configurable. But using the application configuration file is one of the most straightforward solutions.)
Edit:
When deploying your app to another computer, you need to copy its database over too. If you want to use the application on multiple machines and let them connect to the same database, you might want to leave LocalDB and migrate the data to a SQL Server (Express) instance and make it accessible over the (local) network.
Edit 2 (regarding the recent edits in your post):
I see in step 1 that you are using an application setting (called LearningConn) in your solution now. That's fine. However, it is important that you also use that setting in step 2, like this:
SqlConnection connect = new SqlConnection(Properties.Settings.Default.LearningConn);
If you change the setting in Visual Studio, it will update the connection string. Since the setting will probably have application scope, it will not be possible to update the setting/connection string within your application in runtime (by the user).
I'm not sure if your connection string using |DataDirectory| will always work as expected in all scenarios. I have only been using it in ASP.NET webapplications. If it does work in WinForms applications, you might read this document to learn how to set it up. But personally I am somewhat sceptical about this approach.
I personally would opt for a solution where you use a placeholder in your connection string, which you replace with the full path to the .mdf file before you pass it to your SqlConnection constructor.
When you use "{DBFILE}" as the placeholder, for example, the value of your LearningConn setting would look like this:
Data
Source=(LocalDB)\MSSQLLocalDB;AttachDbFilename={DBFILE};Integrated
Security=True;Connect Timeout=30
(Note that this value should be a single line without any line breaks!)
You might create a separate setting in your application called DbFile (of type string) to store the actual value that should be put in place of {DBFILE} in your connection string. When you use scope "user" for that setting, the value might be changed from within the application by the user. When saved, it might not be saved directly in the application's configuration file, however, but in an additional configuration file hidden somewhere in the user's Windows user profile. You might read this document to learn more about application settings.
Your code in step 2 might eventually look something like this:
string connectString = Properties.Settings.Default.LearningConn;
string dbFile = Properties.Settings.Default.LearningSystemDb;
connectString = connectString.Replace("{DBFILE}", dbFile);
SqlConnection connect = new SqlConnection(connectString);
To let your application's users select and store the database .mdf file to use, you might include (a variation of) the following code in your application somewhere:
using (var dlg = new System.Windows.Forms.OpenFileDialog())
{
dlg.Title = "Select database file to use";
dlg.Filter = "Database Files (*.mdf)|*.mdf";
dlg.CheckFileExists = true;
if (dlg.ShowDialog() == System.Windows.Forms.DialogResult.OK)
{
Properties.Settings.Default.DbFile = dlg.FileName;
Properties.Settings.Default.Save();
}
}
Your question is not clear!
you need work with one Database on 2 or more PC?!
OR
you need work with 2 separate programs?
if you need 2 separate programs :
you must copy .mdf file to other PC at same address or keep mdf address in app.config and read it before connect to SQL.
How to Read From app.config
if you need work with one Db you must connect to dataBase Server such as SQL Server and keep connection string in app.config in connectionStrings tag.
Get connection string from App.config
If you want to work on other PCs, rather than building it dynamically make the connection string more generic:
Server=(localdb)\\mssqllocaldb;Database=LearningSystem;Trusted_Connection=True;MultipleActiveResultSets=true
This should create the mdf file under 'mssqllocaldb' in %appdata% for each user. You might need LocalDb installed (which you tick during SQL Server installation)
I have worked with EF for a while now and i have always used LocalDb's for storing data. I want to start working with SQL Server databases instead but I'm having some issues setting up the connection string.
https://msdn.microsoft.com/en-us/library/jj653752(v=vs.110).aspx#sse
https://www.connectionstrings.com/
and looked over google but none of the answers made it work in my case so I must be doing something wrong (some of the connections strings throw an exception others didn't but wouldn't insert anything either into the database neither)
My question is when working with EF & SQL Server, should I use both the connection string in the App.config & setting the path of the DB in the CTOR of the context (by using AppDomain.CurrentDomain.SetData("DataDirectory", path);) or is the app.config sufficient ?
I have tried the following connection strings:
Data Source=.\GURUBEAST-PC\GURUSQL;Initial Catalog=iManager;Trusted_Connection=True;MultipleActiveResultSets=True;
Data Source=.\GURUBEAST-PC\GURUSQL;Database=iManager;Integrated Security=True;Trusted_Connection=True;MultipleActiveResultSets=True;
Data Source=.\GURUBEAST-PC\GURUSQL;AttachDbFilename=C:\Program Files\Microsoft SQL Server\MSSQL11.GURUSQL\MSSQL\DATA\iManager.mdf;Database=iManager;Trusted_Connection=True;MultipleActiveResultSets=True;
Data Source=.\GURUBEAST-PC\GURUSQL;AttachDbFilename=C:\Program Files\Microsoft SQL Server\MSSQL11.GURUSQL\MSSQL\DATA\iManager.mdf;Database=iManager;Trusted_Connection=True;
Data Source=.\GURUBEAST-PC\GURUSQL;Database=iManager;Trusted_Connection=True;
Data Source=.\GURUBEAST-PC\GURUSQL;Initial Catalog=iManager;Integrated Security=SSPI;
Data Source=.\GURUBEAST-PC\GURUSQL;Initial Catalog=iManager;User id=GURUBEAST-PC\GuruBeast;
Where "iManager" is the name of the database. I use Windows auth for my SQL Server instance.
What am I doing wrong ? Should I set my path to the program files folder or the App_Data (I have seen both and tried both but both didn't work)?
Kind regards!
The Data Source key is used to find the machine on which the Sql Server instance runs.
You can have different strings for it but the most common used in a LAN environment is composed using the name of the server machine followed by an eventual instance name.
So, if your local PC is named GURUBEAST-PC and, at install time, you haven't specified any instance name, the connectionstring Data Source contains only the name of the machine GURUBEAST-PC. If you have an instance name then you should add that instance name to you Data Source key. GURUBEAST-PC\GURUSQL
This will guarantee to all the PC in the same LAN the possibility to have the same connectionstring also if the connection is made from the same PC where the SQL Server runs.
If the Data Source points at the local pc, you can use many shortcuts to represent the local PC:
(LOCAL)
localhost
.
\.
and eventually add the instance name to these shortcuts without repeating the PC name
Once you get your host name figured out, Entity Framework will generate your connection string for you. Here's a sample of what your connection string could look like if you were attempting to connect to AdventureWorks database hosted on your local instance of SQL Server 2014 aptly named sql2014.
<connectionStrings>
<add name="AdventureWorksEntities" connectionString="metadata=res://*/DataModels.AdventureWorksDb.csdl|res://*/DataModels.AdventureWorksDb.ssdl|res://*/DataModels.AdventureWorksDb.msl;provider=System.Data.SqlClient;provider connection string="data source=.\sql2014;initial catalog=AdventureWorks;persist security info=True;user id=App_AdventureWorks;password=asdasdfasdfasdf;MultipleActiveResultSets=True;App=EntityFramework"" providerName="System.Data.EntityClient" />
</connectionStrings>
Your db context would then look something like this.Again, EF generates this for you.
public partial class AdventureWorksEntities : DbContext
{
public AdventureWorksEntities()
: base("name=AdventureWorksEntities")
{
}
I'd like to know how to link my WCF application with a remote SQL Server database. By remote, I mean that is on the same network than me but not on the same computer/project.
I've the controll of the computer where the database is stored on.
What I've done so far : create my WCF application and try to add an ADO.NET connection. My issue : where to find the name of the server ? (and also : is it the good way to proceed ?).
Thanks !
where to find the name of the server?
Three options:
whoever "owns" the database server tells you the details, and you put them in a configuration file (or some other configuration system)
whoever "owns" the database server tells some key user the details, and the user puts them into a screen / api in the application
something like the above, but you try to discover sql servers at runtime via SqlDataSourceEnumerator (not a fan of this option, to be honest)
Conntion string should look like
Server=myServerName\myInstanceName;Database=myDataBase;User Id=myUsername;Password=myPassword;
In Place of myServerName you can use IPAdress of machine
I suggest you add connectionString in the Web.config file of the application
<add name="connectionString"
connectionString="Data Source=ServerName/PC-Name;Initial Catalog=DatabaseName;User ID=userid;Password=pass"
providerName="System.Data.SqlClient" />
Use the connection string in your code/Logic
string conn = ConfigurationManager.ConnectionStrings["connectionString"].ConnectionString;
Currently I am using SQL Server CE for persisting my data for which I am providing with a .sdf and connection string mentioned in app.config pointing to this .sdf file.
Now I want to provide user with the flexibility to have the data stored in their own SQL Server database if present at there disposal.
Now I am facing the problem of how to change the connection string at runtime if user chooses to uses its own database ?
Or if restrict them to use my predefined .mdf file how to attach that in their SQL Server ?
My recommendation would be to have 2 connection strings in the configuration file (app or web). There is a special section for them intuitively called ConnectionStrings. You can then switch between them based on other settings.
Changing connection strings dynamically is actually pretty easy to do as long as you have a place to store the new settings (ie. web or app config files). If you provide a way for them to enter the server information you can use the ConfigurationManager class to update your app/web.config.
Ado.net typically has parameters on almost any db connection object that allows you to specify the connection string as an arguement. Additionally, there are helper classes that can be used to construct the connection string on the fly like the SqlConnectionStringBuilder or EntityConnectionStringBuilder. I personally love the Entity Framework as it allows you to create the database from the model itself if it does not already exist, provided you already have the connection string.
c#.Net 3.5 with a SQL Server 2000 backend, I have a connection string in my app.config file that looks like this
<add name="MFG_ConnectionString"
connectionString="Provider=SQLOLEDB;Data Source=MFG;Persist Security Info=True;Password=kb1234;User ID=kb;Initial Catalog=MFG"
providerName="System.Data.OleDb" />
This connection string was built with the data source configuration wizard. Creating a dataset with this and dragging the DataSource element to create a DataGridView populates and successfully allows all CRUD operations.
However, I'm not looking to make changes to this through a databound form. I'm looking to do this behind the scenes in code. Since this is an older version of SQL Server I'm assuming I must use OleDbConnection and other OleDb objects to get the job done. When I try to execute the following:
OleDbConnection visualConnection = new OleDbConnection(ConfigurationManager.ConnectionStrings["MFG_ConnectionString"].ConnectionString);
I get an exception: "Keyword not supported 'provider'.
Yet if I take out provider I'm told that I must supply one. Not sure why this works through the dataset on the form yet I cannot create my own connection object... any thoughts?
EDIT It should be noted that when I originally created the connection to this database, it told me that the database I was trying to connect to did NOT support SqlConnection and that I must choose another (my choice being OleDb at that time). It is odd to me that this connection works behind the scenes as SqlConnection without provider in the connection string but the dataset then breaks...
SqlConnection works fine with SQL 2000. You can get a connectionstring sample here