校验 [英] checksum

问题描述

我想知道PGSQL是否具有类似于
MS SQL Server 2000的binary_checksum（）的功能。在比较行时它非常方便

数据而不是必须写长布尔表达式。

binary_checksum（）获取字段列表并返回一个整数值

sumarize行内容。


谢谢，

美联储

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解决方案

>我想知道PGSQL是否具有类似于MS SQL Server 2000的binary_checksum（）

的功能。在比较数据行而不是拥有数据时非常方便编写长布尔表达式。
binary_checksum（）接受一个字段列表，它返回一个整数值
，它会对行内容进行优化。

在类似的说明中，我发现自己想要一个扩展的''=''运算符

意思是

（a = b或（a为null）和b是空的））


当然是相同的目标，进行更一般的比较...


d。

-

David Helgason，

商业发展等，

超越边缘I / S（ http://otee.dk ）

直线+45 2620 0663

主线+45 3264 5049

在2004年9月26日19:58，Federico Balbi写道：

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David Helgason写道：

我想知道PGSQL是否具有类似于MS / SQL Server 2000的binary_checksum（）的功能。它非常方便它来比较数据行而不必写长布尔表达式。
binary_checksum（）接受一个字段列表，它返回一个整数值
，它会对行内容进行优化。

您可以使用md5函数....例如：


从bar中选择md5（foo），其中baz = 2;


J


在类似的说明中，我发现自己已经一个扩展的''=''运算符
意思是
（a = b或（a为空，b为空））

同样的目标当然是更一般的比较......

d。

-

命令提示，Inc。，Mammoth PostgreSQL的主页 - S / ODBC和S / JDBC

Postgresql支持，编程共享主机和专用主机。

+ 1-503-667-4564 - [e-mail] - http：//www.commandprompt。 com

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> David Helgason写道：

我想知道PGSQL是否具有类似
binary_checksum（）的功能
MS SQL Server 2000.在比较数据行而不必编写长布尔表达式时非常方便。
binary_checksum（）接受一个字段列表并返回一个整数值
对行内容进行sumarize。

您可以使用md5函数....例如：

选择md5（foo）来自bar，其中baz = 2;

看起来md5（）只接受一个字符串。我需要通过字段

代替。我正在查看文档，我想我可以写

类似于：


field1，field2，...，fieldn = expr1，expr2 ,. ..，exprn


这样一个操作员将检查所有字段是否相等。


美联储

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Hi,
I was wondering if PGSQL has a function similar to binary_checksum() of
MS SQL Server 2000. It is pretty handy when it comes to compare rows of
data instead of having to write long boolean expressions.
binary_checksum() takes a list of fields and it returns an integer value
which sumarize the row content.

Thanks,
Fed
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解决方案

> I was wondering if PGSQL has a function similar to binary_checksum()

of
MS SQL Server 2000. It is pretty handy when it comes to compare rows of
data instead of having to write long boolean expressions.
binary_checksum() takes a list of fields and it returns an integer
value
which sumarize the row content.

On a similar note, I''ve found myself wanting an extended ''='' operator
meaning
(a = b or (a is null and b is null))

same goal of course, for more general comparisons...

d.
--
David Helgason,
Business Development et al.,
Over the Edge I/S (http://otee.dk)
Direct line [phone]
Main line [phone]
On 26. sep 2004, at 19:58, Federico Balbi wrote:
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David Helgason wrote:

I was wondering if PGSQL has a function similar to
binary_checksum() of
MS SQL Server 2000. It is pretty handy when it comes to compare rows of
data instead of having to write long boolean expressions.
binary_checksum() takes a list of fields and it returns an integer value
which sumarize the row content.

You could use the md5 function.... such as :

select md5(foo) from bar where baz = 2;

J

On a similar note, I''ve found myself wanting an extended ''='' operator
meaning
(a = b or (a is null and b is null))

same goal of course, for more general comparisons...

d.

--
Command Prompt, Inc., home of Mammoth PostgreSQL - S/ODBC and S/JDBC
Postgresql support, programming shared hosting and dedicated hosting.
[phone] - [e-mail] - http://www.commandprompt.com
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> David Helgason wrote:

I was wondering if PGSQL has a function similar to
binary_checksum() of
MS SQL Server 2000. It is pretty handy when it comes to compare rows of
data instead of having to write long boolean expressions.
binary_checksum() takes a list of fields and it returns an integer value
which sumarize the row content.

You could use the md5 function.... such as :

select md5(foo) from bar where baz = 2;

Looks like md5() takes only a string. I need to pass alist of fields
instead. I was looking at the documentattion and I think I can write
soemthing like:

field1, field2, ..., fieldn = expr1, expr2, ..., exprn

This way one operator will check all the fields for equality.

Fed
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