57
votes

I am newbie in this .NET and please don't mind in answering my simple question. I am trying to write a windows application, where in I am using a localhost SQLserver for database.

I need to know what is the exact connection string for my localhost, if my server name looks like as below:

Data Source=HARIHARAN-PC\SQLEXPRESS;Initial Catalog=master;Integrated Security=True

should i need to give this same as connection string, or is something wrong in this syntax.

whn i try to open my connection. I am seeing error in opening connection.

How the format of connection string should be? any one please guide me.

I tried like this :

 private void button1_Click(object sender, EventArgs e)
    {
        string str = "Data Source=HARIHARAN-PC\SQLEXPRESS;Initial Catalog=master;Integrated Security=True" ; 
        SqlConnection con = new SqlConnection(str);
        SqlCommand cmd = new SqlCommand();
        SqlDataReader r;

        cmd.CommandText = "SELECT * from Table1";
        cmd.CommandType = CommandType.Text;
        cmd.Connection = con;

        con.Open();

        r = cmd.ExecuteReader();

        con.Close();


    }

This code errors out at con.Open();

13
Which type of "authentication mode" you are using ?? Is it "Windows Authentication mode" or "SQL Server mode (Mixed mode)" ?? You should use user id and password in your connection string. - Krishnraj Rana
What kind of error are you seeing? - svick

13 Answers

85
votes

Using the default instance (i.e., MSSQLSERVER, use the DOT (.))

<add name="CONNECTION_STRING_NAME" connectionString="Data Source=.;Initial Catalog=DATABASE_NAME;Integrated Security=True;" />
20
votes

Choose a database name in Initial Catalog

Data Source=HARIHARAN-PC\SQLEXPRESS;Initial Catalog=your database name;Integrated Security=True" ;

see more

9
votes

Do You have Internal Connection or External Connection. If you did Internal Connection then try this:

"Data Source=.\SQLEXPRESS;AttachDbFilename="Your PAth .mdf";Integrated Security=True;User Instance=True";
8
votes

Try this connection string.

Data Source=HARIHARAN-PC\\SQLEXPRESS;Initial Catalog=yourDataBaseName;Integrated Security=True

See this link for more details http://msdn.microsoft.com/en-us/library/system.data.sqlclient.sqlconnection.connectionstring%28v=vs.110%29.aspx

8
votes
<add name="connstr" connectionString="Data Source=localhost;Initial Catalog=DBName;User Id=username;Password=password" providerName="System.Data.SqlClient"/>

The above also works. It ignores the username and password passed in in the connection string. I switched from an environment db to a local one, and it works fine even though my user in the connection string does not exist in this context.

6
votes

You can also use Dot(.) for local key i.e;

Data Source=.\SQLEXPRESS;Initial Catalog=master;Integrated Security=True

If you have the default server instance i.e. MSSQLSERVER, then just use dot for Data Source.

Data Source=.;Initial Catalog=master;Integrated Security=True
4
votes

use this connection string :

Server=HARIHARAN-PC\SQLEXPRESS;Intial Catalog=persons;Integrated Security=True;

rename person with your database name

4
votes

In .Net configuration I would use something like:

"Data Source=(localdb)\\MSSQLLocalDB;Initial Catalog=..."

This information is from https://www.connectionstrings.com/sql-server-2016/

3
votes
public string strConnectionstring = "Data Source=(LocalDB)\\MSSQLLocalDB;AttachDbFilename=|DataDirectory|\\DataBaseName.mdf";
2
votes
string str = "Data Source=HARIHARAN-PC\\SQLEXPRESS;Initial Catalog=master;Integrated Security=True" ;
2
votes
string str = @"Data Source=HARIHARAN-PC\SQLEXPRESS;Initial Catalog=master;Integrated Security=True" ;
1
votes

When using SQL Express, you need to specify \SQLExpress instance in your connection string:

string str = "Data Source=HARIHARAN-PC\\SQLEXPRESS;Initial Catalog=master;Integrated Security=True" ;
0
votes
Data Source=HARIHARAN-PC\SQLEXPRESS; Initial Catalog=Your_DataBase_name; Integrated Security=true/false; User ID=your_Username;Password=your_Password;

To know more about connection string Click here