Clarified Azure login requirements per VSTS 1202392. (#4865)

Author: douglaslMS

docs/framework/data/adonet/connection-string-syntax.md

@@ -39,7 +39,7 @@ Each .NET Framework data provider has a `Connection` object that inherits from <
 -   <xref:System.Data.OracleClient.OracleConnectionStringBuilder>  
 
  The connection string builders allow you to construct syntactically valid connection strings at run time, so you do not have to manually concatenate connection string values in your code. For more information, see [Connection String Builders](../../../../docs/framework/data/adonet/connection-string-builders.md).  
-  
+
 ## Windows Authentication  
  We recommend using Windows Authentication (sometimes referred to as *integrated security*) to connect to data sources that support it. The syntax employed in the connection string varies by provider. The following table shows the Windows Authentication syntax used with the .NET Framework data providers.  
 
@@ -54,9 +54,13 @@ Each .NET Framework data provider has a `Connection` object that inherits from <
 >  `Integrated Security=true` throws an exception when used with the `OleDb` provider.  
   
 ## SqlClient Connection Strings  
- The syntax for a <xref:System.Data.SqlClient.SqlConnection> connection string is documented in the <xref:System.Data.SqlClient.SqlConnection.ConnectionString%2A?displayProperty=nameWithType> property. You can use the <xref:System.Data.SqlClient.SqlConnection.ConnectionString%2A> property to get or set a connection string for a SQL Server database. If you need to connect to an earlier version of SQL Server, you must use the .NET Framework Data Provider for OleDb (<xref:System.Data.OleDb>). Most connection string keywords also map to properties in the <xref:System.Data.SqlClient.SqlConnectionStringBuilder>.  
-  
- Each of the following forms of syntax will use Windows Authentication to connect to the **AdventureWorks** database on a local server.  
+The syntax for a <xref:System.Data.SqlClient.SqlConnection> connection string is documented in the <xref:System.Data.SqlClient.SqlConnection.ConnectionString%2A?displayProperty=nameWithType> property. You can use the <xref:System.Data.SqlClient.SqlConnection.ConnectionString%2A> property to get or set a connection string for a SQL Server database. If you need to connect to an earlier version of SQL Server, you must use the .NET Framework Data Provider for OleDb (<xref:System.Data.OleDb>). Most connection string keywords also map to properties in the <xref:System.Data.SqlClient.SqlConnectionStringBuilder>.  
+
+> [!IMPORTANT]
+>  The default setting for the `Persist Security Info` keyword is `false`. Setting it to `true` or `yes` allows security-sensitive information, including the user ID and password, to be obtained from the connection after the connection has been opened. Keep `Persist Security Info` set to `false` to ensure that an untrusted source does not have access to sensitive connection string information.  
+
+### Windows authentication with SqlClient 
+ Each of the following forms of syntax uses Windows Authentication to connect to the **AdventureWorks** database on a local server.  
 
 ```  
 "Persist Security Info=False;Integrated Security=true;  
@@ -67,26 +71,26 @@ Each .NET Framework data provider has a `Connection` object that inherits from <
     database=AdventureWorks;server=(local)"  
 ```  
 
-### SQL Server Logins  
+### SQL Server authentication with SqlClient   
  Windows Authentication is preferred for connecting to SQL Server. However, if SQL Server Authentication is required, use the following syntax to specify a user name and password. In this example, asterisks are used to represent a valid user name and password.  
 
 ```  
 "Persist Security Info=False;User ID=*****;Password=*****;Initial Catalog=AdventureWorks;Server=MySqlServer"  
 ```  
-  
-> [!IMPORTANT]
->  The default setting for the `Persist Security Info` keyword is `false`. Setting it to `true` or `yes` allows security-sensitive information, including the user ID and password, to be obtained from the connection after the connection has been opened. Keep `Persist Security Info` set to `false` to ensure that an untrusted source does not have access to sensitive connection string information.  
-  
- To connect to a named instance of SQL Server, use the *server name\instance name* syntax.  
+
+When you connect to Azure SQL Database or to Azure SQL Data Warehouse and provide a login in the format `user@servername`, make sure that the `servername` value in the login matches the value provided for `Server=`.
+
+> [!NOTE]
+>  Windows authentication takes precedence over SQL Server logins. If you specify both Integrated Security=true as well as a user name and password, the user name and password will be ignored and Windows authentication will be used.  
+
+### Connect to a named instance of SQL Server
+To connect to a named instance of SQL Server, use the *server name\instance name* syntax.  
 
 ```  
 Data Source=MySqlServer\MSSQL1;"  
 ```  
-  
- You can also set the <xref:System.Data.SqlClient.SqlConnectionStringBuilder.DataSource%2A> property of the `SqlConnectionStringBuilder` to the instance name when building a connection string. The <xref:System.Data.SqlClient.SqlConnection.DataSource%2A> property of a <xref:System.Data.SqlClient.SqlConnection> object is read-only.  
-  
-> [!NOTE]
->  Windows authentication takes precedence over SQL Server logins. If you specify both Integrated Security=true as well as a user name and password, the user name and password will be ignored and Windows authentication will be used.  
+ 
+You can also set the <xref:System.Data.SqlClient.SqlConnectionStringBuilder.DataSource%2A> property of the `SqlConnectionStringBuilder` to the instance name when building a connection string. The <xref:System.Data.SqlClient.SqlConnection.DataSource%2A> property of a <xref:System.Data.SqlClient.SqlConnection> object is read-only.  
 
 ### Type System Version Changes  
  The `Type System Version` keyword in a <xref:System.Data.SqlClient.SqlConnection.ConnectionString%2A?displayProperty=nameWithType> specifies the client-side representation of [!INCLUDE[ssNoVersion](../../../../includes/ssnoversion-md.md)] types. See <xref:System.Data.SqlClient.SqlConnection.ConnectionString%2A?displayProperty=nameWithType> for more information about the `Type System Version` keyword.