字符串与数字类型 [英] String vs Numeric Type
问题描述
如果我决定将主键设为一串数字
vs实际数字会不会有意义？在
效率方面，它会对DB2产生什么影响吗？为什么你会为一个字符串选择数字？
不需要是数字格式？
谢谢
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would it matter if I decided to make a primary key a string of numbers
vs actual numbers ? would it make any difference to DB2 in terms of
efficiency ? why would you choose numeric over a string for a key that
does not need to be in numeric format ?
thanks
--
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推荐答案
Victor Mehta写道：
Victor Mehta wrote:
是否重要我决定将一个主键与一些数字相对于实际数字？它在效率方面对DB2有什么影响吗？你为什么要在字符串上选择数字来表示
不需要数字格式的键？
would it matter if I decided to make a primary key a string of numbers
vs actual numbers ? would it make any difference to DB2 in terms of
efficiency ? why would you choose numeric over a string for a key that
does not need to be in numeric format ?
可能是物理数据库中最重要的区别级别是
INTEGER需要4个字节的存储空间，而你需要
CHAR（10）来存储相同的值范围。
但是，这绝不应该在物理数据库级别决定。
您的数据模型将（应该）始终确定适当的域名
您的属性。
Probably the most significant difference at a physical database level is
the fact that INTEGERs require 4 bytes of storage, while you would need
CHAR(10) to store the same range of values.
However, this should never be decided at a physical database level.
Your data model will (should) always determine the proper domain for
your attributes.
Ian写道：
Victor Mehta写道：
Victor Mehta wrote:
如果我决定是否重要使主键成为一串数字
vs实际数字？它在效率方面对DB2有什么影响吗？为什么你会为字符串选择数字而不需要数字格式？
would it matter if I decided to make a primary key a string of numbers
vs actual numbers ? would it make any difference to DB2 in terms of
efficiency ? why would you choose numeric over a string for a key that
does not need to be in numeric format ?
物理数据库级别上最重要的区别可能是
然而，这绝不应该在物理上决定数据库级别。
您的数据模型将（应该）始终确定您的属性的正确域。
Probably the most significant difference at a physical database level is
the fact that INTEGERs require 4 bytes of storage, while you would need
CHAR(10) to store the same range of values.
However, this should never be decided at a physical database level.
Your data model will (should) always determine the proper domain for
your attributes.
确实！我刚刚与一位客户对抗，其中设备ID是一个编码的bb。 比特范围是指比特范围。实现为INTEGER。
接下来我听到的是为什么DB2不支持UNSIGNED INTEGER因为
我们松开了0x8000000位。
在经过一些患者解释并指向
a混合环境中的小端和大端后，他们现在正朝着CHAR（4）for BIT DATA（又名
BINARY）的方向前进。
数据类型没有事后的想法....
干杯
Serge
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Serge Rielau
DB2 SQL编译器开发
IBM多伦多实验室
Indeed! I''ve just been butting heads with a customer where a "device ID"
which is an "encoding" of "bit ranges" was implemented as INTEGER.
Next thing I hear is "Why doesn''t DB2 support UNSIGNED INTEGER because
we loose the 0x8000000 bit."
After some patient explanation and pointing to little and big endian in
a mixed environment they are inching towards CHAR(4) FOR BIT DATA (aka
BINARY) now.
Data types are no afterthought....
Cheers
Serge
--
Serge Rielau
DB2 SQL Compiler Development
IBM Toronto Lab
最终，所有数据都存储为位，因此INDEXed的数据类型应该是无关紧要的。就个人而言，我尝试使用INTEGER作为我的PRIMARY KEYs，
，因为我喜欢将TABLE称为对象，而个人
记录为这些对象的实例。在大多数每个
表格中都有一个名为Id的表。让它永远是一个INTEGER非常方便
和一致。另外，如果另一个TABLE是参考这个TABLE，则不需要一个
长的字符串，只需一个（相对）小的INTEGER。
还有其他我喜欢它的原因。我发现当文本用于
标识符时，文本可能会随着时间而改变。一个非描述性的INTEGER
不应该是一个很好的主要关键。然后我将改为
字符字段UNIQUE。
所以，我只是觉得使用INTEGER更合适。
也可以使用字符串。
B.
Ultimately, all data is stored as bits, so the data type INDEXed should
be irrelevant. Personally, i try to use INTEGER as my PRIMARY KEYs,
because i like to refer to TABLEs as objects, and the individual
records as instances of those objects. Having a COLUMN in most every
TABLE called "Id" and having it always be an INTEGER is very convenient
and consistant. Plus, if another TABLE is to REFERENCE this TABLE, a
long character string is not needed, just a (relatively) small INTEGER.
There are other reasons i like it. I find that when text is used for an
identifier, the text may change over time. A non-descript INTEGER
shouldn''t and therefore makes an excellent PRIMARY KEY. I''ll then make
the character field UNIQUE instead.
So, i simply find the use of an INTEGER to be better fitted.
A string can be used just as well.
B.
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