Previous Row Comparison

2 Message(s) by 2 Author(s) originally posted in mysql discussion

From: Legend

Date: Saturday, October 20, 2007

I have a table

<database> A collection of {records} in a {relational database}.

	(1997-06-04)

in this format:

Column A | Column B
1 | 2
1 | 3
1 | 4
2 | 5
.....
.....

What I want to do is something like this:

If in Column A there is a change in the number i.e. from the above
table there were many 1s which transitioned into a 2. I want to record
this change. I want to extract these two rows into another table. How
can I make this possible?

From: Kees Nuyt

Date: Saturday, October 20, 2007

On Sat, 20 Oct 2007 05:37:38 -0000, Legend
wrote in message:

I have a table in this format:
Column A | Column B
1 | 2
1 | 3
1 | 4
2 | 5
.....
.....
What I want to do is something like this:
If in Column A there is a change in the number i.e. from the above
table there were many 1s which transitioned into a 2. I want to record
this change. I want to extract these two rows into another table. How
can I make this possible?

With a trigger.
--
( Kees
)
c[_] Famous last words - Do not worry, I can handle

1. <programming, operating system> A simple item of data that
	identifies a resource.  For example, a {Unix} file handle
	identifies an open file and associated data such as whether it
	was opened for read or write and the current read/write
	position.  On the {Macintosh}, a handle is a pointer to a
	pointer to some dynamically-allocated memory.  The extra level
	of indirection allows on-the-fly {memory compaction} or
	{garbage collection} without invalidating application program
	references to the allocated memory.

	2. <jargon> An alias used intended to conceal a user's true
	identity in an electronic message.  The term is common on
	Citizen's Band and other amateur radio but, in that context
	usually means the user's real name as {FCC} rules forbid
	concealing one's identity.

	Use of grandiose handles is characteristic of {crackers},
	{weenies}, {spods}, and other lower forms of network life;
	true hackers travel on their own reputations.

	Compare {nick}.

	[{Jargon File}]

	(2004-07-20)

it. (#441)

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