title: "Commands and Tables | Microsoft Docs"

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Command and Table Classes

The [ATL OLE DB Consumer Wizard](../../atl/reference/atl-ole-db-consumer-wizard.md) lets you specify whether you want a command or table object.

title: "Creating a Project for the Provider | Microsoft Docs"

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The **New Project** dialog box appears.

1. In the **Name** box, enter a name for the project, and then click **OK**.

title: "Creating an OLE DB Consumer Using a Wizard | Microsoft Docs"

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The last two sections explain the wizard-generated OLE DB consumer code.

title: "Creating an OLE DB Consumer | Microsoft Docs"

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This section covers the following topics:

Next, you must make sure your provider contains all the functionality to support anything the consumer might request of it. If the consumer wants to update the data store, the provider has to contain code that persists data to the data store. For example, you might use the C Run-Time Library or MFC to perform such operations on your data source. The section "[Writing to the Data Source](#vchowwritingtothedatasource)" describes how to write to the data source, deal with NULL and default values, and set column flags.

Note that `IRowsetUpdateImpl` derives from `IRowsetChangeImpl`. Thus, `IRowsetUpdateImpl` gives you change capability plus batch capability.

1. In your rowset class, inherit from `IRowsetChangeImpl` or `IRowsetUpdateImpl`. These classes provide appropriate interfaces for changing the data store:

```

> [!NOTE]

1. Add the following to your COM map (`BEGIN_COM_MAP ... END_COM_MAP`):

You can find the values used in these macro calls by looking in Atldb.h for the property IDs and values (if Atldb.h differs from the online documentation, Atldb.h supersedes the documentation).

> [!NOTE]

**If you implement IRowsetChangeImpl**

- `DBPROP_MAXPENDINGROWS`.

> [!NOTE]

To read from the data source, call the `Execute` function. To write to the data source, call the `FlushData` function. (In a general sense, flush means to save modifications you make to a table or index to disk.)

FlushData(HROW, HACCESSOR);

- Provide an implementation of `FlushData`.

Typically, the biggest challenge is working with your own native data store. If possible, try to:

The best thing to do is to have actual specified values in your data store for NULL and default values. It is best if you can extrapolate this data. If not, you are advised not to allow NULL and default values.

As with NULL data, you have the responsibility to deal with changing default values.

virtual HRESULT SetDBStatus(DBSTATUS* pdbStatus, CSimpleRow* pRow,

title: "Data Sources and Sessions | Microsoft Docs"

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- [CDataSource](../../data/oledb/cdatasource-class.md) This class instantiates the data source object, which creates and manages a connection to a data source through an OLE DB provider. The data source takes information such as the data source address and authentication information in the form of a connection string.

- [CSession](../../data/oledb/csession-class.md) This class instantiates the session object, which represents a single access session to the data source. However, you can create multiple sessions on a data source. For each session, you can create rowsets, commands, and other objects to access data from the data source. The session handles transactions.

- You can use the ITEST utility that comes with Visual C++.

1. Open the provider project.

- You support an element such as bookmarks that adds columns.

1. Remove any `PROVIDER_COLUMN_MAP`s from your code.

The PROVIDER_COLUMN_ENTRY macros normally handle the `IColumnsInfo::GetColumnsInfo` call. However, because a consumer might choose to use bookmarks, the provider must be able to change the columns returned depending on whether the consumer asks for a bookmark.

class CAgentMan

{

public:

Next, implement the `GetColumnInfo` function in MyProviderRS.cpp, as shown in the following code.

To check for the `DBPROP_BOOKMARKS` property, `GetColumnInfo` uses the `IRowsetInfo` interface, which you can obtain by calling `QueryInterface` on the `pRowset` interface. As an alternative, you can use an ATL [CComQIPtr](../../atl/reference/ccomqiptr-class.md) method instead.

ATLCOLUMNINFO* CAgentMan::GetColumnInfo(void* pThis, ULONG* pcCols)

{

static ATLCOLUMNINFO _rgColumns[5];