SQL Server Data Access Components (SDAC) 是一组存取SQL Server数据库的非可视控件，今天在盒子上看到这个控件，发行版本居然都V4.3了，怎么以前没有听说过呢，据说这个比ADO效率要高很多，我还没试过，只是据说，今天装上了，已经是破解版，带源码的，先学习一下。
|SQL Server Data Access Components Overview|
Compatibility with Other Connectivity Methods
How Does SDAC Work?
SDAC allows you to connect to SQL Server through OLE DB, which is the lowest documented SQL Server interface.
SDAC connects through OLE DB through a set of COM-based interfaces. SDAC is designed to be lightweight and consists of a minimal layer between your code and SQL Server databases.
In comparison, the Borland Database Engine (BDE) uses several layers to access SQL Server, and requires additional data access software to be installed on client machines.
The BDE data transfer protocol is shown below.
BDE Connection Protocol
SDAC allows you to avoid using BDE and DBLibrary.
SDAC Connection Flow
All editions of SDAC include the following basic components:
SDAC Professional Edition includes the following additional components:
The following list describes the main features of SQL Server Data Access Components.