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Using Oledb connection string for Localhost c#

When use Oledb c# connection
I noticed that a lot connection using file.
But how to connect to localhost using oledb?
I created database and tables using Microsoft SQL Server Management that connect with SQL Express and using window authentication
When using this function i don't know how should convert to connect to localhost
//Want the connString to connect localhost instead of file
public static string connString = #"Provider=Microsoft.JET.OLEDB.4.0;data source=" + Path + "\\database\\errDB.mdb";
public static OleDbConnection connection;
public myFunction()
{
string sqlString = "SELECT name,contact,accessLevel,Crudential_ID FROM errors where Crudential_ID =#ID";
connection = new OleDbConnection(connString);
OleDbCommand command = new OleDbCommand(sqlString, connection);
//Open connection
connection.Open();
command.Parameters.Add("#ID", OleDbType.VarChar);
command.Parameters["#ID"].Value = "test";
//Read from database
OleDbDataReader reader = command.ExecuteReader();
if(reader.HasRows)
{
.....
}
connection.Close();
}

connectionstrings.com - true to its name - is indispensable when you frequently need to construct connection strings. For your specific case, this would be the relevant section.
Based on that, your connection string should look something like this:
Provider=SQLNCLI11;Server=.\SQLEXPRESS;Database=SOMEDATABASE;Trusted_Connection=yes;
To break it down:
SQLNCLI11 is the SQL Native Client OLEDB provider. You can see available providers in SQL Management Studio, under Server Objects > Linked Servers > Providers.
.\SQLEXPRESS is your servername and instance. The . is shorthand for localhost (you can also use localhost if you prefer), and SQLEXPRESS is the default instance name that SQL Express installs under.
SOMEDATABASE - whatever your database name is.
Trusted_Connection=yes - Use windows authentication. Sometime you see it as Integrated Security=SSPI. They are one and the same.

If you are using SQL Express then I would suggest using a System.Data.SqlClient.SqlConnection object to make your connection. You will only need your server name to connect.
Server=ServerName\SQLEXPRESS;Database=Blah;User ID=user;Password=pw

Remote server claims table doesn't exist

I have a connection string in my config files like so
add name="entities" connectionString="Data Source=localhost;user id=username;password=somepassword;persist security info=True;database=dbname" providerName="MySql.Data.MySqlClient"
This works with localhost.
As soon as I change the Data Source to Data Source=123.34.45.56 <-- some remote server
I get MySql.Data.MySqlClient.MySqlException: Table 'mydb.Emails' doesn't exist
If I use connection code in c# it will work against the remote server : Example below
MySql.Data.MySqlClient.MySqlConnection mySqlConnection = new
MySql.Data.MySqlClient.MySqlConnection();
mySqlConnection.ConnectionString = "Data Source=123.34.45.56;user id=username;password=somepassword;persist security info=True;database=dbname";
string conString = mySqlConnection.ConnectionString;
using (MySqlConnection connection = new MySqlConnection(conString)) {
connection.Open();
using (MySqlCommand command = new MySqlCommand(
"SELECT * FROM emails",
connection)) {
using (MySqlDataReader reader = command.ExecuteReader()) {
while (reader.Read()) {
for (int i = 0; i < reader.FieldCount; i++) {
var tr = reader.GetValue(i);
}
}
}
}
}
How come the connection string in the web.config is throwing this error for every table MySql.Data.MySqlClient.MySqlException: Table 'mydb.Emails'doesn't exist.
The tables are there as the c# connection code can open a connection and query the data just fine.
How do I get the connection string to work?

John Garrard was correct. It was a case sensitivity issue with the database located on two different operating systems. I needed to make my entities case sensitive and the switching the connection string will work between the Windows development machine and the Linux production machine. Thanks.

I came across this issue when moving from a Windows dev to AWS test system. There is a parameter called "lower_case_table_names" that controls how MySql matches table names which defaults to 0 on linux and 1 in Windows (meaning case sensitive and insensitive):
On your AWS Console go to the RDS page.
Click on Parameter Groups.
Either create your own or click into the default parameter group.
Search for the parameter lower_case_table_names.
Edit the value and set it to 1
Save the parameters and restart the db instance.

MySQL Connection with C#

I have a code written in JAVA:
String host = "jdbc:mysql://online/find";
String username = "test";
String password = "test";
And its working fine. But I want to use the same database MySQL with C#. And I am doing this:
try
{
string myConnStr = "Server=//online/find; " +
" Port = 3306; "+
" DATABASE=finder; " +
" UID=test;Password=test;";
MySqlConnection MySqlConn = new MySqlConnection(myConnStr);
MySqlDataAdapter MySqlAdapter = new MySqlDataAdapter();
MySqlAdapter.SelectCommand = new MySqlCommand("Select * from finder.Customer", MySqlConn);
MySqlCommandBuilder cb = new MySqlCommandBuilder(MySqlAdapter);
MySqlConn.Open();
DataSet ds = new DataSet();
MessageBox.Show("Connected");
MySqlConn.Close();
}
But I am getting Error: "Unable to connect to any of the specified mysql hosts"
I even tried with
IP address in connection string but still its not working.
I have checked these posts already:
Unable to connect to any of the specified mysql hosts. C# MySQL
unable to connect to any of the specified mysql hosts. c#

According to the documentation should be:
string myConnStr =
"Database=finder;Data Source=//online/find;Port=3306;User Id=test;Password=test";
However for me Connection strings could be hard to remember.
Its very easy to make a mistake when you write it manually.
One advice is to use the server explorer to connect to your database. Then right click on your database icon > select properties ... you will see the connection string copy and paste .
Voilà!
Server Explorer:
Properties:

Did you install the MySQl Connector for Microsoft Application. If yes then add a reference to MySql.dll from your C# application, then use the below connection string
string myConnStr = "server=yourMySqlServerHostorIP; port=MySqlPort;uid=username;pwd=password;initial catalog=dbname";
To download mysql connector go to http://dev.mysql.com/downloads/connector/net/.
Let me know if it works.

My first idea about the issue is "this has nothing to do with param names for username and password". You are not getting an error like:
user "null" cant login
Java and C# work on totally different foundation (Oracle vs. Microsoft) I don't know Java but I think the libraries for connecting to a remote location must be different.
I think the host URL you used is the problem:
Server=//online/find;
I use MySQL with my C# projects and I define the host value as:
localhost or 127.0.0.1
an IP address (xxx.xxx.xxx.xxx)
a host url (my.dbserver.com)
here is a working MySQL connection string:
<add name="dbConnNews"
connectionString="server=xx.xx.xx.xx;database=yyyyy;User
Id=zzzzzz;Password=**********;"
providerName="MySql.Data.MySqlClient" />

Try to connect to the server via IDE Server Explorer --> Data Connections and observe the connection string generated.

While I connect to database using ADO.NET there is an error

While I establish a connection to SQL Server using ADO.NET, it showing errors.
Following is the code:
SqlConnection con = new SqlConnection("Data Source=.\\SQLEXPRESS;Initial Catalog=abdul;Integrated Security=true");
SqlCommand cmd = new SqlCommand();
con.Open();
String str="select * from emp where empname='Abdul'";
cmd = new SqlCommand(str, con);
SqlDataReader dr = cmd.ExecuteReader();
if (dr == null || !dr.HasRows)
{
MessageBox.Show("No Records found");
}
else
{
while (dr.Read())
{
textBox1.Text = dr[0].ToString();
textBox2.Text = dr[1].ToString();
}
}
When I am running the project it showing the following error:
Cannot open database "abdul" requested by the login. The login failed.
What have to do?

The login is successful at the the SQL Server level. Then either
the database exists but the login you are using doesn't have access to the database
the database doesn't exist
In SSMS, go to adbul database. Expand the security node and add the relevant users (which map to the login) + security there. If you still can't, have you created the database single user?
It's hard to give more details at the moment.

You need to check that the user you are connecting with is a valid SQL Login, and that the password supplied is correct. You also need to ensure the login has an associated SQL User in the database they are trying to connect to.
SQL Logins are used to access the server itself, and they are mapped to database SQL users.

You said you created the database. How did you do this? Was it from sql management studio? If so, was this in the same Windows session as you are executing the program code above?
I ask because if you could create a database, I believe you should be able to connect to it.
I'd look at the difference between successfully connecting with Sql Management Studio and trying to get past the 3rd line of code in your question. (assuming that's where it fails, maybe even edit the question to take out the lines beyond).

Can't connect to database server

I'm encountering a problem with my database connection.
I started with a new blank solution, then I added a WCF library project, and last but not least a WCF website (service).
In the website i added a reference to the library where I have the interface (data contract), the class that implements the interface and the dataclasses.
what I'm trying to do is to connect to a database on a server and try to retrieve some data from there.
So the connection string looks like:
<add name="myConnectionString" connectionString="Data Source=MyServer; Initial Catalog=MyDatabase; User Id=me; Password=me123;" providerName="System.Data.SqlClient" />
and this is how I'm trying to connect with the database:
public List<string> GetEngagements(string id)
{
string sql = "SELECT myColumn FROM myTable WHERE Id = '" + id + "'";
string connString = string.Empty;
SqlConnection connDB;
connString = ConfigurationManager.ConnectionStrings["myConnectionString"].ConnectionString;
connDB = new SqlConnection(connString);
SqlCommand command = new SqlCommand(sql, connDB);
connDB.Open();
SqlDataReader rdr = command.ExecuteReader();
List<string> numbers = new List<string>();
while (rdr.Read())
{
numbers.Add(rdr[0].ToString());
}
rdr.Close();
return numbers;
}
I'm getting an exception on connDB.Open().
Then exception message says:
Failed to generate a user instance of SQL Server due to a failure in starting the process for the user instance. The connection will be closed.
I've been getting this message for 2 days now, I've googled a lot and deleted the C:\Documents and Settings\username\Local Settings\Application Data\Microsoft\Microsoft SQL Server Data\SQLEXPRESS directory but it didn't work for me..
Any solution???? help please

The error message:
Failed to generate a user instance of SQL Server due to a failure in starting the process for the user instance.
Suggests that you're using user instancing, and therefore your connection string will point to an .mdf file on disk rather than the name of a database.
So I'll assume that you want to connect to a file instance rather than a server instance.
I'll also assume that you're using SqlExpress rather than the full fat version.
In which case your connection string is wrong. It should look more like this:
"Data Source=.\SQLEXPRESS;
AttachDbFilename=fileOnDisk.mdf;
Integrated Security=True;
User Instance=True;"
User instancing means that this server instance and the DB inside will only be visible to the application opening the connection string.
You don't have to use user instancing - you can set User Instance=False or just leave it out. Then once the application has made the connection you can connect other tools to the server instance and connect to the DB yourself.