Connecting to database using code - C#

Question

When I use server explorer in Visual Studio and add a local DB on my D drive, I get a connection string and the connection test is successful.

But when I want to use that connection string like below to attach the database without the wizard and jut by code, I get an error on opening the connection, my connection string is provided below:

string coonection_string ="Data Source=(LocalDB)\v11.0;AttachDbFilename=D:\\x\book.mdf;Integrated Security=True;Connect Timeout=30";

try
{
      SqlConnection myconnection = new SqlConnection(coonection_string);
      myconnection.Open();
      MessageBox.Show(" connected");
}
catch (Exception e1)
{
      MessageBox.Show(e1.ToString());
}

The first thing I would try is getting rid of the double back slash here: D:\\... — Phil Walton
– Phil Walton, Commented May 2, 2015 at 7:24
You are not helping yourself. Saying I have an error and not telling us what is this error is a bit useless. Now you can hope that someone has a crystall ball and can see your monitor from here... (or can you tell us that pesky error message?) By the way, it is MessageBox.Show(e1.Message) — Steve
– Steve, Commented May 2, 2015 at 7:37

Community · Accepted Answer · 2017-05-23 10:24:06Z

1

Your connection string is wrong. Eigher mdf file in your local project or sqlexpres or you can use a database name in the connection string like

Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|MyDatabase.mdf;Integrated Security=True;User Instance=True

or 

Data Source=(LocalDb)\v11.0;Initial Catalog=MyDatabase;Integrated Security=SSPI;

Check this link.

DB Connection string in Web.config to use attached .mdf database won't work

Always use Web.config file for connection string and access the entry in code as

Dim mWebSvr As String = ConfigurationSettings.AppSettings("Connectionstring")

edited May 23, 2017 at 10:24

CommunityBot

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answered May 2, 2015 at 7:27

Ajay2707

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Comments

BSG · Accepted Answer · 2015-05-02 07:32:20Z

1

Try to put @ before connection string. We use @ before strings to avoid having to escape special characters.

string coonection_string =@"Data Source=(LocalDB)  \v11.0;AttachDbFilename=D:\\x\book.mdf;Integrated Security=True;Connect Timeout=30";

answered May 2, 2015 at 7:32

BSG

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Midhun Mundayadan · Accepted Answer · 2015-05-02 07:41:56Z

1

Keep an @ symbol in-front of the connection string,in C# backslash is a escape character

string coonection_string =@"Data Source=(LocalDB)\v11.0;AttachDbFilename=D:\\x\book.mdf;Integrated Security=True;Connect Timeout=30";

else your connection string may not be in correct format

SqlConnectionStringBuilder.AttachDBFilename Property

edited May 2, 2015 at 7:41

answered May 2, 2015 at 7:28

Midhun Mundayadan

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2 Comments

Alex Over a year ago

So, using the @ for escaping what does @"D:\\x\book.mdf" become?

Midhun Mundayadan Over a year ago

@Alex it needs to be change like this @"D:\x\book.mdf"

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