A connection string is a string consists of information needed to connect to a data store. It is passed via code to an underlying driver or provider in order to initiate the connection. It is commonly used to connect to a database, but you can also connect to a spreadsheet or text file using connection string and ADO.Net. The connection string may include attributes such as the name of the driver, server and database, as well as security information such as user name and password.

.NET Framework provides a set of data providers that serves as a bridge between an application and a data source. A data provider is used to retrieve data from a data source and to reconcile changes to that data back to the data source.

To connect to SQL Server, .Net Framework provides three main Data Providers: SqlClient Data Provider, OleDb Data Provider, and Odbc Data Provider. Each data provider uses different connection strings for different types of connections.

Below is given the list of connection strings used with different ADO.Net data providers to connect to SQL Server database:

ADO.Net Data Provider

Connection Type

Connection Strings

SqlClient Data Provider

Standard Security

Data Source= DatabaseServerName;Initial Catalog=DatabaseName; User Id=myUsername;Password=myPassword;

OR

Server= DatabaseServerName; Database=DatabaseName; User ID=myUsername; Password=myPassword; Trusted_Connection=False;

Trusted Connection

Data Source= DatabaseServerName;Initial Catalog= DatabaseName;Integrated Security=SSPI;

OR

Server= DatabaseServerName;Database=myDataBase;Trusted_Connection=True;

Via IP Address

Network Library=DBMSSOCN; Data Source=xxx.xxx.xxx.xxx,1433; Initial Catalog= DatabaseName; User Id=myUserName; Password=myPassword;

OLE DB Data Provider

Standard Security

Provider=sqloledb;Data Source=DatabaseServerName;Initial Catalog=DatabaseName;User Id=myUsername;Password=myPassword;

Trusted Connection

Provider=sqloledb;Data Source= DatabaseServerName;Initial Catalog= DatabaseName;Integrated Security=SSPI;

Via IP Address

Driver=SQLOLEDB; Network Library=DBMSSOCN; Data Source=xxx.xxx.xxx.xxx,1433; Initial Catalog= DatabaseName; User id=myUserName; Password=myPassword;

ODBC Data Provider

Using DSN

Dsn=DsnName; Uid=myUserName; Pwd=myPassword;

Standard Security

Driver={SQL Server}; Server= DatabaseServerName; DataBase= DatabaseName; Uid=myUserName; Pwd=myPassword;

Trusted Connection

Driver={SQL Server}; Server= DatabaseServerName; DataBase= DatabaseName; Uid=; Pwd=;

OR

Driver={SQL Server}; Server= DatabaseServerName; DataBase= DatabaseName; Trusted_Connection=Yes;

Sometime you may also need to connect to an SQL Server instance. In that case, use “DatabaseServerName\InstanceName” as the Data Source/Server in the connection string.

The syntax of specifying the server instance in the value of the Data Source/Server key is the same for all connection strings for SQL Server. The below is given an example of connection string to connect to an SQL Server Instance:

Data Source=DatabaseServerName\InstanceName; Initial Catalog=DatabaseName; User Id=myUsername; Password=myPassword;