How much effort will the migration require?

In order to understand how much effort a given DB-Library-to-Client-Library migration will take, you need to examine the DB-Library application in terms of what tasks it performs and what routines it uses.

Some DB-Library tasks, such as sending a SQL command to a server, are straightforward in both libraries.

Other tasks, such as using Open Server registered procedures, are more complex in Client-Library.

The following table classifies typical DB-Library application tasks according to the degree of effort required to duplicate the same application functionality with Client-Library:

**Table 2-1: DB-Library tasks ranked by migration effort required**
DB-Library task	Partial list of related routines	Degree of effort required for migration	Notes
Sending a Transact-SQL language command to a server	dbcmd, dbfcmd, dbsqlexec	Less than average	Sending language commands is straightforward in Client-Library.
Sending an RPC command to a server.	dbrpcinit, dbrpcparam, dbrpcsend	Less than average	Sending RPC commands is straightforward in Client-Library.
Inserting and retrieving text and image data from a server	dbreadtext, dbwritetext, dbtxtptr, dbtxtimestamp	Less than average	Client-Library handles text and image data more gracefully than DB-Library.
Manipulating datetime values	dbdatename, dbdatepart, dbdatezero	Average	Client-Library does not provide direct equivalents for these routines. Instead, use cs_dt_crack and cs_dt_info.
Automatic result row formatting	dbprhead, dbprrow, dbspr1row, dbsprhead	Average	Client-Library does not provide equivalent routines, which can easily be replaced by application code such as that found in the exutils.c Client-Library example program. Applications that use these routines for debugging purposes can use ct_debug instead.
Bulk copy operations	Bulk copy routines	Average	DB-Library’s bcp_ routines include built-in file I/O routines, which read and write host data files and format files, and write error files. Client-Library applications use Bulk-Library, which does not include file I/O routines.
Use pointers to result data instead of binding the data	dbdata, dbadata	Average	Currently, Client-Library applications are required to bind results to memory in the application’s data space.
Row buffering	DBCURROW, DBFIRSTROW, DBLASTROW, dbsetrow	More than average	Client-Library provides cursor and array-binding functionality as an alternative to row buffering. Using cursors to replace row buffering may require some application design work.
Registered procedures	dbnpcreate, dbnpdefine, dbregdrop	More than average	Client-Library does not provide equivalent routines. Client-Library applications must send RPC commands to invoke the Open Server system registered procedures sp_regcreate and sp_regdrop to create and drop registered procedures.
Read and write Adaptive Server pages	dbreadpage, dbwritepage	Do not convert	Client-Library does not support this functionality.
Two-phase commit	Two-phase commit routines	Do not convert	Client-Library does not provide equivalent routines. Instead, Client-Library supports transaction monitors to control transactions. The Sybase World Wide Web site (http://www.sybase.com) provides an example program that performs two-phase commit with Client-Library. The illustrated technique relies on the use of undocumented Adaptive Server system stored procedures. As with any undocumented interface, Sybase does not guarantee support or maintenance of this interface.