使用C#连接本地SQL服务器数据库

Question

Suppose I have created a SQL Server database called Database1.mdf in the App_Data folder in Visual Studio with a table called Names .

How could I establish a connection to read the table values using C#?

So far I've tried something like this:

SqlConnection conn = new SqlConnection("Server=localhost;Database=Database1;");

conn.Open();

// create a SqlCommand object for this connection
SqlCommand command = conn.CreateCommand();
command.CommandText = "Select * from Names";

But I get an error:

database not found/error connecting to database

Answer 1

In Data Source (on the left of Visual Studio) right click on the database, then Configure Data Source With Wizard . A new window will appear, expand the Connection string, you can find the connection string in there

Answer 2

If you use SQL authentication , use this:

using System.Data.SqlClient;

SqlConnection conn = new SqlConnection();
conn.ConnectionString = 
     "Data Source=.\SQLExpress;" + 
     "User Instance=true;" + 
     "User Id=UserName;" + 
     "Password=Secret;" + 
     "AttachDbFilename=|DataDirectory|Database1.mdf;"
conn.Open();

If you use Windows authentication , use this:

using System.Data.SqlClient;
SqlConnection conn = new SqlConnection();
conn.ConnectionString = 
     "Data Source=.\SQLExpress;" + 
     "User Instance=true;" + 
     "Integrated Security=true;" + 
     "AttachDbFilename=|DataDirectory|Database1.mdf;"
conn.Open();

Answer 3

SqlConnection c = new SqlConnection(@"Data Source=localhost; 
                           Initial Catalog=Northwind; Integrated Security=True");

Answer 4

If you're using SQL Server express, change

SqlConnection conn = new SqlConnection("Server=localhost;" 
       + "Database=Database1;");

to

SqlConnection conn = new SqlConnection("Server=localhost\SQLExpress;" 
       + "Database=Database1;");

That, and hundreds more connection strings can be found at http://www.connectionstrings.com/

Answer 5

您尝试使用此字符串连接

Server=.\SQLExpress;AttachDbFilename=|DataDirectory|Database1.mdf;Database=dbname; Trusted_Connection=Yes;

Answer 6

I like to use the handy process outlined here to build connection strings using a .udl file. This allows you to test them from within the udl file to ensure that you can connect before you run any code.

Hope that helps.

Answer 7

Visual Studio 2019 (and probably a few previous versions).

• View -> SQL Server Object Explorer
• Top of the tree is 'SQL Server'
• Under 'SQL Server', are couple of '(localdb)....'
• Expand the (localdb)... -> Databases until you find your db.
• Database Name (eg. Database1) -> Right-click -> Properties, and scroll the many properties (eg. "ANSI NULL Default"). Find the "Connection string" property, copy the value into your code, and you're running.