使用一些疯狂的构造和应用逻辑，而不是简单的COALESCE。

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.

使用ORM进行批量更新 选择多于需要的数据。同样，这通常在使用ORM时完成 在循环中触发sql。 没有良好的测试数据，只在实时数据上注意到性能下降。

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?)

对于基于sql的数据库:

Not taking advantage of CLUSTERED INDEXES or choosing the wrong column(s) to CLUSTER. Not using a SERIAL (autonumber) datatype as a PRIMARY KEY to join to a FOREIGN KEY (INT) in a parent/child table relationship. Not UPDATING STATISTICS on a table when many records have been INSERTED or DELETED. Not reorganizing (i.e. unloading, droping, re-creating, loading and re-indexing) tables when many rows have been inserted or deleted (some engines physically keep deleted rows in a table with a delete flag.) Not taking advantage of FRAGMENT ON EXPRESSION (if supported) on large tables which have high transaction rates. Choosing the wrong datatype for a column! Not choosing a proper column name. Not adding new columns at the end of the table. Not creating proper indexes to support frequently used queries. creating indexes on columns with few possible values and creating unnecessary indexes. ...more to be added.

认为他们是dba和数据建模师/设计人员，而他们在这些领域没有任何正式的灌输。 认为他们的项目不需要DBA，因为这些东西都很简单/琐碎。 未能正确区分应该在数据库中完成的工作和应该在应用程序中完成的工作。 未验证备份，或未备份。 在他们的代码中嵌入原始SQL。