What is DAO

DAO has access to local and remote data sources. If the data source is local or client-side, the DAO accesses the data through the jet engine, and the latest DAO3.6 is accessed through ODBCDirect if the data source is remote or ODBC-driven.
Note: In fact, ODBCDirect is a RDO that uses DAO names, and when ODBCDirect is used, DAO is not installed with the Microsoft Jet database engine, but is loaded RDO2.0.
With the introduction of ADO, DAO's advantages are no longer reflected, so in the near future, DAO will gradually withdraw from the stage of history. However, as a mature technology, DAO has been widely used for a period of time, DAO users will still have a large number of existence. In general, developers can use DAO in the following situations.
(1) The application system uses a local database, such as Microsoft FoxPro and Microsoft Access.
(2) The user has been very proficient in DAO, but there is no time to learn ODBC or ADO.
(3) Users need to modify an existing system, and the original system is DAO, and large-scale, it will be transplanted into ADO a lot of time and money.

The DAO hides the technical details of the backend data source, and the developer does not have to consider the differences between the different database systems.

For example, the following code can work on any type of data source:
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