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?)

不对数据库模式使用版本控制 直接针对活动数据库工作 没有阅读和理解更高级的数据库概念(索引、聚集索引、约束、物化视图等) 没有测试可伸缩性……只有3或4行的测试数据永远不会给您真实的实时性能的真实画面

我想补充一点: 偏好“优雅”代码而不是高性能代码。在应用程序开发人员看来，对数据库最有效的代码通常是丑陋的。

Believing that nonsense about premature optimization. Databases must consider performance in the original design and in any subsequent development. Performance is 50% of database design (40% is data integrity and the last 10% is security) in my opinion. Databases which are not built from the bottom up to perform will perform badly once real users and real traffic are placed against the database. Premature optimization doesn't mean no optimization! It doesn't mean you should write code that will almost always perform badly because you find it easier (cursors for example which should never be allowed in a production database unless all else has failed). It means you don't need to look at squeezing out that last little bit of performance until you need to. A lot is known about what will perform better on databases, to ignore this in design and development is short-sighted at best.

使用一些疯狂的构造和应用逻辑，而不是简单的COALESCE。

因为“它太神奇了”或“不在我的数据库中”这样的原因，而放弃像Hibernate这样的ORM。 过度依赖像Hibernate这样的ORM，并试图将它硬塞到不合适的地方。

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.