我不得不说，应用程序开发人员犯的最大错误是没有正确地规范化数据库。

作为一名应用程序开发人员，我意识到正确的数据库结构、规范化和维护的重要性;我花了无数的时间自学数据库结构和管理。根据我的经验，每当我开始与不同的开发人员合作时，我通常必须重组整个数据库并更新应用程序以适应，因为它通常是畸形的和有缺陷的。

For example, I started working with a new project where the developer asked me to implement Facebook Connect on the site. I cracked open the database to see what I had to work with and saw that every little bit of information about any given user was crammed into one table. It took me six hours to write a script that would organize the table into four or five separate tables and another two to get the app to use those tables. Please, normalize your databases! It will make everything else less of a headache.

这里有一个视频链接，名为“经典数据库开发错误和克服它们的五种方法”，作者是Scott Walz

开发人员所犯的关键数据库设计和编程错误

Selfish database design and usage. Developers often treat the database as their personal persistent object store without considering the needs of other stakeholders in the data. This also applies to application architects. Poor database design and data integrity makes it hard for third parties working with the data and can substantially increase the system's life cycle costs. Reporting and MIS tends to be a poor cousin in application design and only done as an afterthought. Abusing denormalised data. Overdoing denormalised data and trying to maintain it within the application is a recipe for data integrity issues. Use denormalisation sparingly. Not wanting to add a join to a query is not an excuse for denormalising. Scared of writing SQL. SQL isn't rocket science and is actually quite good at doing its job. O/R mapping layers are quite good at doing the 95% of queries that are simple and fit well into that model. Sometimes SQL is the best way to do the job. Dogmatic 'No Stored Procedures' policies. Regardless of whether you believe stored procedures are evil, this sort of dogmatic attitude has no place on a software project. Not understanding database design. Normalisation is your friend and it's not rocket science. Joining and cardinality are fairly simple concepts - if you're involved in database application development there's really no excuse for not understanding them.

不了解数据库并发模型以及它如何影响开发。事后添加索引和调整查询很容易。然而，应用程序的设计没有适当考虑热点，资源争用 和正确的操作(假设您刚刚阅读的内容仍然有效!)可能需要在数据库和应用层中进行重大更改，以便稍后纠正。

根据我的经验: 不与有经验的dba沟通。

1)不了解如何正确地在Java和数据库之间进行交互。

2)过度解析，不恰当或没有重用SQL

3)没有使用BIND变量

4)在数据库中使用SQL集逻辑时，用Java实现过程逻辑(更好)。

5)在投入生产前没有进行任何合理的性能或可伸缩性测试

6)使用水晶报表，在报表中没有正确设置模式名

7)由于不了解执行计划，使用笛卡尔式产品实现SQL(你甚至看了EXPLAIN计划吗?)