Open Client supports a text datatype, CS_TEXT, a unitext datatype, CS_UNITEXT, an image datatype, CS_IMAGE:
CS_TEXT corresponds to the server datatype text, which describes a variable-length column containing up to 2,147,483,647 bytes of printable character data.
CS_UNITEXT corresponds to the server datatype unitext. As with text, unitext describes a variable length column containing up to 2,147,483,647 bytes of printable data. The difference is that unitext character data is stored with Unicode UTF-16 encoding rather than the default character set on the server.
CS_IMAGE corresponds to the server datatype image, which describes a variable-length column containing up to 2,147,483,647 bytes of binary data.
Small text, unitext and image data values require no special handling. Result values can be bound to program variables and subsequently fetched, and input data values can be entered into a database using the Transact-SQL insert and update commands. However, when text, unitext and image values are large, it is usually more practical for an application to use routines that allow the text, unitext or image data to be handled one chunk at a time.
These routines are:
ct_data_info, which sets or retrieves a CS_IODESC structure. A CS_IODESC structure describes the text, unitext or image data that is to be read from or written to the server.
ct_get_data, which reads a chunk of data from the result stream.
ct_send_data, which writes a chunk of data to the command stream.
For more information about text, unitext and image data processing, see the “text and image Data Handling” topics page in the Open Client Client-Library/C Reference Manual.
