Best design for edit tracking?

Hey all,
This is a general question. Here's my scenario: We have a legacy
database. The core table within contains almost 4 million records in
SQL Server. Currently we have a web front end which allows uses to
search through the database for the information they need.
What the client wants is a web front end which allows some users to
edit the core table above. No problem. What the client also wants is
for the non-editable web front end (used for research) to display (via
colored text) which records have been edited. Example:
1.) Jimmy edits records x, y, and z in coretable1 using the editing
web app.
2.) Jane comes along and uses the research web app to hunt down some
records. She views records s through z. In her view she notices that
certain cells in rows x, y, and z are colored red. This tells her that
Jimmy has edited those specific fields in those specific rows.
My question is: what is the most efficient way to track these column
specific edits so that my web app can display them? This may seem like
a web dev question, but the reality is that my web apps have to
interact with SQL Server so if anyone has any input, I'd love to hear
it! Thanks.OK, the quickest solution to this goest something like this...
Add two rows to your core table, the first is a DateTime with a Default
constraint of GetDate(). The second column is used to identify who made the
change.
Next when update one of the rows, you need to simply include the identifier
of the person who made the change.
Next when you read the table you need to read and compare two rows. The
most recent row, and the second most recent row. This provides the
information about what changed - as a freebie you'll gain access to the old
version of the row.
Another approach would be to have two tables. The first is the core table
as it is now. The second table contains a flag for each column in your core
table, the DateTime column (as above) and the user identifier column (as
above). This time when you edit the row, you also place a new row into this
table settings the flags for the columns which were altered. Don't forget
to include a foreign key back to your core table. When you select the row
from the core table you can also join on your change map, selecting the
max(datetime) and this will tell what columns were changed in the last edit.
But it won't tell you the values that they were before. There is a big
advantage in this method as your core table doesn't need to be altered.
Regards
Colin Dawson
www.cjdawson.com
"roy.@.nderson@.gm@.il.com" <roy.anderson@.gmail.com> wrote in message
news:1147534237.719954.218790@.j33g2000cwa.googlegroups.com...
> Hey all,
> This is a general question. Here's my scenario: We have a legacy
> database. The core table within contains almost 4 million records in
> SQL Server. Currently we have a web front end which allows uses to
> search through the database for the information they need.
> What the client wants is a web front end which allows some users to
> edit the core table above. No problem. What the client also wants is
> for the non-editable web front end (used for research) to display (via
> colored text) which records have been edited. Example:
> 1.) Jimmy edits records x, y, and z in coretable1 using the editing
> web app.
> 2.) Jane comes along and uses the research web app to hunt down some
> records. She views records s through z. In her view she notices that
> certain cells in rows x, y, and z are colored red. This tells her that
> Jimmy has edited those specific fields in those specific rows.
> My question is: what is the most efficient way to track these column
> specific edits so that my web app can display them? This may seem like
> a web dev question, but the reality is that my web apps have to
> interact with SQL Server so if anyone has any input, I'd love to hear
> it! Thanks.
>|||Colin
> Add two rows to your core table, the first is a DateTime with a Default
> constraint of GetDate(). The second column is used to identify who made
> the change.
I think you menat "add to columns", and it is worth mentioning that with
this solutuin you will have to write a trigget on that table in order to
track changes
"Colin Dawson" <newsgroups@.cjdawson.com> wrote in message
news:yRn9g.68620$wl.14113@.text.news.blueyonder.co.uk...
> OK, the quickest solution to this goest something like this...
> Add two rows to your core table, the first is a DateTime with a Default
> constraint of GetDate(). The second column is used to identify who made
> the change.
> Next when update one of the rows, you need to simply include the
> identifier of the person who made the change.
> Next when you read the table you need to read and compare two rows. The
> most recent row, and the second most recent row. This provides the
> information about what changed - as a freebie you'll gain access to the
> old version of the row.
> Another approach would be to have two tables. The first is the core table
> as it is now. The second table contains a flag for each column in your
> core table, the DateTime column (as above) and the user identifier column
> (as above). This time when you edit the row, you also place a new row
> into this table settings the flags for the columns which were altered.
> Don't forget to include a foreign key back to your core table. When you
> select the row from the core table you can also join on your change map,
> selecting the max(datetime) and this will tell what columns were changed
> in the last edit. But it won't tell you the values that they were before.
> There is a big advantage in this method as your core table doesn't need to
> be altered.
> Regards
> Colin Dawson
> www.cjdawson.com
>
> "roy.@.nderson@.gm@.il.com" <roy.anderson@.gmail.com> wrote in message
> news:1147534237.719954.218790@.j33g2000cwa.googlegroups.com...
>|||oops, I did mean columns yes.
A trigger won't really be able to help as you'll need to supply extra
information than what is stored in the original table. It would be better
to use a Stored procedure and directly enter the data into the new columns.
Of course, the exception to this is that if the application connects to SQL
using seperate usernames, it is possible to use the @.@.User in a trigger to
accomplish the same result. With the applications that my company creates,
this is not possible as they alway connect with the same user (connection
pooling)
Regards
Colin Dawson
www.cjdawson.com
"Uri Dimant" <urid@.iscar.co.il> wrote in message
news:uSloXSxdGHA.4108@.TK2MSFTNGP03.phx.gbl...
> Colin
> I think you menat "add to columns", and it is worth mentioning that with
> this solutuin you will have to write a trigget on that table in order to
> track changes
>
> "Colin Dawson" <newsgroups@.cjdawson.com> wrote in message
> news:yRn9g.68620$wl.14113@.text.news.blueyonder.co.uk...
>|||On 13 May 2006 08:30:37 -0700, roy.@.nderson@.gm@.il.com wrote:

>Hey all,
>This is a general question. Here's my scenario: We have a legacy
>database. The core table within contains almost 4 million records in
>SQL Server. Currently we have a web front end which allows uses to
>search through the database for the information they need.
>What the client wants is a web front end which allows some users to
>edit the core table above. No problem. What the client also wants is
>for the non-editable web front end (used for research) to display (via
>colored text) which records have been edited. Example:
>1.) Jimmy edits records x, y, and z in coretable1 using the editing
>web app.
>2.) Jane comes along and uses the research web app to hunt down some
>records. She views records s through z. In her view she notices that
>certain cells in rows x, y, and z are colored red. This tells her that
>Jimmy has edited those specific fields in those specific rows.
>My question is: what is the most efficient way to track these column
>specific edits so that my web app can display them? This may seem like
>a web dev question, but the reality is that my web apps have to
>interact with SQL Server so if anyone has any input, I'd love to hear
>it! Thanks.
Hi Roy,
This is impossible to answer, because the requirements are incomplete.
For instance, what happens if Jimmy edits rows x, y, and z (as in your
example), then Joan edits rows w and x, then Jimmy edits z another time
and then Jane views rows s through z. What columns in what rows have to
be marked as "changed"?
Another question - what if Jimmy edits rows x, y, and z; then nothin
happens for a long time. After a year, Jane looks at rows s through z.
Should Jimmy's changes still be marked?
Hugo Kornelis, SQL Server MVP|||>
> My question is: what is the most efficient way to track these column
> specific edits so that my web app can display them? This may seem like
> a web dev question, but the reality is that my web apps have to
> interact with SQL Server so if anyone has any input, I'd love to hear
> it! Thanks.
There are several ways to accomplish that. Do you want your system to
be optimized for retrieval of the current version but support
occasional drill down into editing history. Or do you want to optimize
retrieving history of edits and are ready to pay the price of slowing
down retrieval of current version?