Using ADO with OLE DB Driver for SQL Server

Article
11/18/2022

Applies to: SQL Server Azure SQL Database Azure SQL Managed Instance Azure Synapse Analytics Analytics Platform System (PDW)

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In order to take advantage of new features introduced in SQL Server 2005 (9.x) such as multiple active result sets (MARS), query notifications, user-defined types (UDTs), or the new xml data type, existing applications that use ActiveX Data Objects (ADO) should use the OLE DB Driver for SQL Server as their data access provider.

To enable ADO to use new features of recent versions of SQL Server, some enhancements have been made to the OLE DB Driver for SQL Server, which extends the core features of OLE DB. These enhancements allow ADO applications to use newer SQL Server features and to consume two data types introduced in SQL Server 2005 (9.x): xml and udt. These enhancements also exploit enhancements to the varchar, nvarchar, and varbinary data types. OLE DB Driver for SQL Server adds the SSPROP_INIT_DATATYPECOMPATIBILITY initialization property to the DBPROPSET_SQLSERVERDBINIT property set for use by ADO applications so that the new data types are exposed in a way compatible with ADO. In addition, the OLE DB Driver for SQL Server also defines a new connection string keyword named DataTypeCompatibility that is set in the connection string.

Note

Existing ADO applications can access and update XML, UDT, and large value text and binary field values using the SQLOLEDB provider. The new larger varchar(max), nvarchar(max), and varbinary(max) data types are returned as the ADO types adLongVarChar, adLongVarWChar and adLongVarBinary respectively. XML columns are returned as adLongVarChar, and UDT columns are returned as adVarBinary. However, if you use the OLE DB Driver for SQL Server (MSOLEDBSQL19 or MSOLEDBSQL) instead of SQLOLEDB, you need to make sure to set the DataTypeCompatibility keyword to "80" so that the new data types will map correctly to the ADO data types.

Enabling OLE DB Driver for SQL Server from ADO

To enable the usage of OLE DB Driver for SQL Server, ADO applications will need to implement the following keywords in their connection strings:

Provider=MSOLEDBSQL19
DataTypeCompatibility=80

For more information about the ADO connections string keywords supported in OLE DB Driver for SQL Server, see Using Connection String Keywords with OLE DB Driver for SQL Server.

The following code is an example of establishing an ADO connection string that is fully enabled to work with OLE DB Driver for SQL Server, including the enabling of the MARS feature:

Dim con As New ADODB.Connection

con.ConnectionString = "Provider=MSOLEDBSQL19;" _
         & "Server=(local);" _
         & "Database=AdventureWorks;" _
         & "Use Encryption for Data=Optional;" _
         & "Integrated Security=SSPI;" _
         & "DataTypeCompatibility=80;" _
         & "MARS Connection=True;"
con.Open

Examples

The following sections provide examples of how you can use ADO with the OLE DB Driver for SQL Server.

Retrieving XML column data

In this example, a recordset is used to retrieve and display the data from an XML column in the SQL Server AdventureWorks sample database.

Dim con As New ADODB.Connection
Dim rst As New ADODB.Recordset
Dim sXMLResult As String

con.ConnectionString = "Provider=MSOLEDBSQL19;" _
         & "Server=(local);" _
         & "Database=AdventureWorks;" _
         & "Use Encryption for Data=Optional;" _
         & "Integrated Security=SSPI;" _
         & "DataTypeCompatibility=80;"

con.Open

' Get the xml data as a recordset.
Set rst.ActiveConnection = con
rst.Source = "SELECT AdditionalContactInfo FROM Person.Contact " _
   & "WHERE AdditionalContactInfo IS NOT NULL"
rst.Open

' Display the data in the recordset.
While (Not rst.EOF)
   sXMLResult = rst.Fields("AdditionalContactInfo").Value
   Debug.Print (sXMLResult)
   rst.MoveNext
End While

con.Close
Set con = Nothing

Note

Recordset filtering is not supported with XML columns. If used, an error will be returned.

Retrieving UDT column data

In this example, a Command object is used to execute a SQL query that returns a UDT, the UDT data is updated, and then the new data is inserted back into the database. This example assumes that the Point UDT has already been registered in the database.

Dim con As New ADODB.Connection
Dim cmd As New ADODB.Command
Dim rst As New ADODB.Recordset
Dim strOldUDT As String
Dim strNewUDT As String
Dim aryTempUDT() As String
Dim strTempID As String
Dim i As Integer

con.ConnectionString = "Provider=MSOLEDBSQL19;" _
         & "Server=(local);" _
         & "Database=AdventureWorks;" _
         & "Use Encryption for Data=Optional;" _
         & "Integrated Security=SSPI;" _
         & "DataTypeCompatibility=80;"

con.Open

' Get the UDT value.
Set cmd.ActiveConnection = con
cmd.CommandText = "SELECT ID, Pnt FROM dbo.Points.ToString()"
Set rst = cmd.Execute
strTempID = rst.Fields(0).Value
strOldUDT = rst.Fields(1).Value

' Do something with the UDT by adding i to each point.
arytempUDT = Split(strOldUDT, ",")
i = 3
strNewUDT = LTrim(Str(Int(aryTempUDT(0)) + i)) + "," + _
   LTrim(Str(Int(aryTempUDT(1)) + i))

' Insert the new value back into the database.
cmd.CommandText = "UPDATE dbo.Points SET Pnt = '" + strNewUDT + _
   "' WHERE ID = '" + strTempID + "'"
cmd.Execute

con.Close
Set con = Nothing

Enabling and using MARS

In this example, the connection string is constructed to enable MARS through the OLE DB Driver for SQL Server, and then two recordset objects are created to execute using the same connection.

Dim con As New ADODB.Connection

con.ConnectionString = "Provider=MSOLEDBSQL19;" _
         & "Server=(local);" _
         & "Database=AdventureWorks;" _
         & "Use Encryption for Data=Optional;" _
         & "Integrated Security=SSPI;" _
         & "DataTypeCompatibility=80;" _
         & "MARS Connection=True;"
con.Open

Dim recordset1 As New ADODB.Recordset
Dim recordset2 As New ADODB.Recordset

Dim recordsaffected As Integer
Set recordset1 =  con.Execute("SELECT * FROM Table1", recordsaffected, adCmdText)
Set recordset2 =  con.Execute("SELECT * FROM Table2", recordsaffected, adCmdText)

con.Close
Set con = Nothing

In prior versions of the OLE DB provider, this code would cause an implicit connection to be created on the second execution because only one active set of results could be opened per a single connection. Because the implicit connection wasn't pooled in the OLE DB connection pool, this behavior would cause extra overhead. With the MARS feature exposed by the OLE DB Driver for SQL Server, you get multiple active results on the one connection.