Using IRow::GetColumns in SQL Server Native Client
Applies to: 
SQL Server
Azure SQL Database
Azure SQL Managed Instance
Azure Synapse Analytics
Analytics Platform System (PDW)
The IRow implementation allows forward-only sequential access to the columns. You can either access all the columns in the row with a single call to IRow::GetColumns or call IRow::GetColumns multiple times every time that you access several columns in the row.
The multiple calls to IRow::GetColumns should not overlap. For example, if the first call to IRow::GetColumns retrieves columns 1, 2, and 3, the second call to IRow::GetColumns should call for columns 4, 5, and 6. If later calls to IRow::GetColumns overlap, the status flag (dwstatus field in DBCOLUMNACCESS) is set to DBSTATUS_E_UNAVAILABLE.