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data access 数据访问
odbc stands for open database connectivity
the microsoft open database connectivity (odbc) interface is a c programming language interface that allows applications to access data from a variety of database management systems (dbms).
a set of functions
a means of accessing several databases in different formats
supports both 16-bit and 32-bit apis,
several performance-boosting techniques- connection pooling
the set of api functions is complex, relatively few programmers write applications that directly call odbc functions
dsn
a dsn is a set of values that an application needs to correctly connect to a database.
odbc driver
machine the application runs on connects to a dll called the odbc driver manager, which in turn sends commands to (and retrieves data from) an odbc driver specific to the particular database you want to use.
dao
data control.
this control lets you bind one or more controls on a form to a data source and offers buttons for navigating through the records of the database table you've connected to.
3-tier
3-tier (or n-tier) architectures, where one or more intermediate layers between the application and the database provide services such as data validation, business rules, workload balance, and security. alas, if you want to embrace the n-tier philosophy, you should forget about the data control.
you can use one or more intermediate com components, which consistently implement a more flexible 3-tier design.
rdo
combine the simplicity of dao with the power of direct odbc api programming.
bypasses the jet engine and the dao dll and works directly
resource-hungry jet engine.
ole db
eventually replace odbc as the primary means for connecting to databases.
counterpart to odbc drivers are the ole db providers
ole db is based on com, an architecture that has proven robust enough to move large quantities of data across the.network.
any type of data source, not just relational and isam (indexed sequential access mode) databases
ole db is a comprehensive set of com interfaces for accessing a diverse range of data in a variety of data stores.
