Using SQLPutData to send more than 65,535 bytes of data (for Microsoft® SQL Server™ version 4.21a) or 400 KB of data (for SQL Server 6.0 and later) for a SQL_LONGVARCHAR (text), SQL_WLONGVARCHAR (ntext) or SQL_LONGVARBINARY (image) column, imposes the following restrictions:
Canceling a sequence of SQLPutData calls that provide data to a server running SQL Server in blocks causes a partial update of the column’s value when using version 6.5 or earlier. The text, ntext, or image column referenced when SQLCancel was called will be set to an intermediate “place holder” value.