quartz/content/notes/data-access.md
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2022-05-27 14:12:53 +12:00

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---
title: "data-access"
aliases: Data Access, data access
tags:
- info201
---
Most infosystems require persistent data. e.g.,
- save to file
- save to database
Some systems require several persistent data stores. e.g., multiple databases.
There are three main approaches:
- [file-based-storage](notes/file-based-storage.md)
- [database-based-storage](notes/database-based-storage.md)
# How to manage persistent data access
1. domain objects interact directly with the data store
- write to file or send sql statements
- not easy to change
2. domain objects interact with data store via a mediator
- either standalone class or implementation of a data access interface
- [data-access-object](notes/data-access-object.md)
- encapsulates all access to persistent data
# JDBC
[JDBC](notes/java-database-connectibity.md) is a Framework for working with (SQL) databases in Java. It was designed to be independent of the DBMS you are using. The same java code *should* work on all SQL DBMSs (*just* change the driver)