Fetching a Single Row with IRow (OLE DB Driver)
Applies to: 
SQL Server
Azure SQL Database
Azure SQL Managed Instance
Azure Synapse Analytics
Analytics Platform System (PDW)
The IRow interface implementation in the OLE DB Driver for SQL Server is simplified to increase performance. IRow allows direct access to columns of a single row object. If you know beforehand that the result of a command execution will produce exactly one row, IRow will retrieve the columns of that row. If the result set includes multiple rows, IRow will expose only the first row.
The IRow implementation does not allow any navigation of the row. Each column in the row is accessed only one time with one exception: A column can be accessed one time to find the column size and again to fetch the data.
Note
IRow::Open supports only DBGUID_STREAM and DBGUID_NULL type of objects to be opened.
To obtain a row object using ICommand::Execute method, IID_IRow must be passed. The IMultipleResults interface must be used to handle multiple result sets. IMultipleResults supports IRow and IRowset. IRowset is used for bulk operations.