我们所有使用关系数据库的人都知道(或正在学习)SQL是不同的。获得期望的结果,并有效地这样做,涉及到一个乏味的过程,其部分特征是学习不熟悉的范例,并发现一些我们最熟悉的编程模式在这里不起作用。常见的反模式是什么?


当前回答

我最不喜欢的是

Using spaces when creating tables, sprocs etc. I'm fine with CamelCase or under_scores and singular or plurals and UPPERCASE or lowercase but having to refer to a table or column [with spaces], especially if [ it is oddly spaced] (yes, I've run into this) really irritates me. Denormalized data. A table doesn't have to be perfectly normalized, but when I run into a table of employees that has information about their current evaluation score or their primary anything, it tells me that I will probably need to make a separate table at some point and then try to keep them synced. I will normalize the data first and then if I see a place where denormalization helps, I'll consider it. Overuse of either views or cursors. Views have a purpose, but when each table is wrapped in a view it's too much. I've had to use cursors a few times, but generally you can use other mechanisms for this. Access. Can a program be an anti-pattern? We have SQL Server at my work, but a number of people use access due to it's availabilty, "ease of use" and "friendliness" to non-technical users. There is too much here to go into, but if you've been in a similar environment, you know.

其他回答

反向观点:过度痴迷于正常化。

大多数SQL/ rbdb系统提供了许多非常有用的特性(事务、复制),即使对于非标准化的数据也是如此。磁盘空间很便宜,有时操作/过滤/搜索获取的数据比编写1NF模式更简单(更容易的代码,更快的开发时间),并处理其中的所有麻烦(复杂的连接,讨厌的子选择等)。

我发现过度标准化的系统通常是不成熟的优化,特别是在开发的早期阶段。

(再想想……http://writeonly.wordpress.com/2008/12/05/simple-object-db-using-json-and-python-sqlite/)

不必深入浅出:不使用准备好的语句。

重新使用一个“死”字段来做一些它不打算做的事情(例如在“传真”字段中存储用户数据)-尽管作为一个快速修复非常诱人!

使用SP作为存储过程名称的前缀,因为它将首先在系统过程位置中搜索,而不是自定义过程。

select some_column, ...
from some_table
group by some_column

假设结果将按some_column排序。我在Sybase上看到过这种情况,其中假设成立(目前)。