Either an Open Client library application or an Embedded SQL application can be used to send SQL commands to Adaptive Server.
An Embedded SQL application includes SQL commands in-line. The Embedded SQL precompiler processes the commands into calls to Client-Library routines. All Sybase precompilers 11.0 and later use a runtime library composed solely of documented Client-Library and CS-Library calls. Basically, the precompiler transforms an Embedded SQL application into a Client-Library application, which is then compiled using the host-language compiler.
An Open Client library application sends SQL commands through library routines and does not require a precompiler.
Generally, an Embedded SQL application is easier to write and debug, but a library application can take fuller advantage of the flexibility and power of Open Client routines.