每当我设计数据库时,我总是想知道是否有一种最好的方法来命名数据库中的项目。我经常问自己以下问题:

表名应该是复数吗? 列名应该是单数吗? 我应该为表或列添加前缀吗? 我应该在命名项目时使用大小写吗?

是否有推荐的指导原则来命名数据库中的项?


当前回答

虽然很晚了,但我仍然想对列前缀发表我的意见

对于使用table_column(或tableColumn)列命名标准,似乎有两个主要的论据,都是基于列名本身在整个数据库中是唯一的这一事实:

1)你不需要一直在你的查询中指定表名和/或列别名

2)你可以很容易地在整个代码中搜索列名

我认为这两种观点都有缺陷。不使用前缀解决这两个问题很简单。以下是我的建议:

在SQL中始终使用表名。例如,总是用table。列而不是列。

它显然解决了2)你现在只需要搜索表。而不是table_column。

But I can hear you scream, how does it solve 1)? It was exactly about avoiding this. Yes, it was, but the solution was horribly flawed. Why? Well, the prefix solution boils down to: To avoid having to specify table.column when there's ambiguity, you name all your columns table_column! But this means you will from now on ALWAYS have to write the column name every time you specify a column. But if you have to do that anyways, what's the benefit over always explicitly writing table.column? Exactly, there is no benefit, it's the exact same number of characters to type.

编辑:是的,我知道用前缀命名列可以强制使用正确的用法,而我的方法依赖于程序员

其他回答

Table names should always be singular, because they represent a set of objects. As you say herd to designate a group of sheep, or flock do designate a group of birds. No need for plural. When a table name is composition of two names and naming convention is in plural it becomes hard to know if the plural name should be the first word or second word or both. It’s the logic – Object.instance, not objects.instance. Or TableName.column, not TableNames.column(s). Microsoft SQL is not case sensitive, it’s easier to read table names, if upper case letters are used, to separate table or column names when they are composed of two or more names.

我建议你看看微软的SQL Server样本数据库: https://github.com/Microsoft/sql-server-samples/releases/tag/adventureworks

AdventureWorks示例使用了非常清晰和一致的命名约定,它使用模式名组织数据库对象。

表的单数名称 列的单数名称 表前缀的架构名称(例如:SchemeName.TableName) 帕斯卡壳(又称上驼峰壳)

我知道这有点晚了,这个问题已经得到了很好的回答,但我想就#3关于列名前缀的问题提出我的看法。

所有列都应该使用一个对定义它们的表唯一的前缀命名。

例如,给定表“customer”和“address”,让我们分别使用前缀“cust”和“addr”。"customer"中会有"cust_id", "cust_name"等。“address”将包含“addr_id”,“addr_cust_id”(FK返回给客户),“addr_street”等。

当我第一次看到这个标准时,我坚决反对它;我讨厌这个主意。我无法忍受所有额外的输入和冗余。现在我已经有了足够的经验,我再也不会回去了。

这样做的结果是数据库模式中的所有列都是唯一的。这有一个主要的好处,它压倒了所有反对它的论点(当然,在我看来):

您可以搜索整个代码库,并可靠地找到涉及特定列的每一行代码。

The benefit from #1 is incredibly huge. I can deprecate a column and know exactly what files need to be updated before the column can safely be removed from the schema. I can change the meaning of a column and know exactly what code needs to be refactored. Or I can simply tell if data from a column is even being used in a particular portion of the system. I can't count the number of times this has turned a potentially huge project into a simple one, nor the amount of hours we've saved in development work.

另一个相对较小的好处是,当你进行自连接时,你只需要使用表别名:

SELECT cust_id, cust_name, addr_street, addr_city, addr_state
    FROM customer
        INNER JOIN address ON addr_cust_id = cust_id
    WHERE cust_name LIKE 'J%';

我们的偏好:

Should table names be plural? Never. The arguments for it being a collection make sense, but you never know what the table is going to contain (0,1 or many items). Plural rules make the naming unnecessarily complicated. 1 House, 2 houses, mouse vs mice, person vs people, and we haven't even looked at any other languages. Update person set property = 'value' acts on each person in the table. Select * from person where person.name = 'Greg' returns a collection/rowset of person rows. Should column names be singular? Usually, yes, except where you are breaking normalisation rules. Should I prefix tables or columns? Mostly a platform preference. We prefer to prefix columns with the table name. We don't prefix tables, but we do prefix views (v_) and stored_procedures (sp_ or f_ (function)). That helps people who want to try to upday v_person.age which is actually a calculated field in a view (which can't be UPDATEd anyway). It is also a great way to avoid keyword collision (delivery.from breaks, but delivery_from does not). It does make the code more verbose, but often aids in readability. bob = new person() bob.person_name = 'Bob' bob.person_dob = '1958-12-21' ... is very readable and explicit. This can get out of hand though: customer.customer_customer_type_id indicates a relationship between customer and the customer_type table, indicates the primary key on the customer_type table (customer_type_id) and if you ever see 'customer_customer_type_id' whilst debugging a query, you know instantly where it is from (customer table). or where you have a M-M relationship between customer_type and customer_category (only certain types are available to certain categories) customer_category_customer_type_id ... is a little (!) on the long side. Should I use any case in naming items? Yes - lower case :), with underscores. These are very readable and cross platform. Together with 3 above it also makes sense. Most of these are preferences though. - As long as you are consistent, it should be predictable for anyone that has to read it.

表名:它应该是单数,因为它是一个表示真实世界对象的单数实体,而不是表示对象的单数实体。

列名:它应该是单数,只有这样它才表示它将持有一个原子值,并将确认归一化理论。然而,如果有n个相同类型的属性,那么它们应该以1,2,…作为后缀。n,等等。

表/列前缀:这是一个巨大的主题,将在后面讨论。

外壳:应该是驼色的

我的朋友Patrick Karcher,我请求你不要写任何可能冒犯别人的东西,就像你写的那样,“此外,外键必须在不同的表中一致命名。如果有人不这样做,殴打他应该是合法的。”我从来没有犯过这样的错误,我的朋友帕特里克,但我写一般。如果他们一起打算为此揍你呢?:)