Make Table v. Append to Table: Need Some Expert Design Inputs

[MJ]

I am working on updates to a couple related databases (not linked by any
tables) and have a question about virtues of Make Table vs Append queries.

Make Table: I understand that this will create a NEW table where ever it is
pointed,
so if that table already exists in the destination it
will be deleted, and
the new table written in its place.

Append : In this case I understand that it would require a little more
"work" to
do same as Make Table, i.e. clearing out table before
appending data.

The 1st major difference, other than additional steps, I can see is if you
have a table structure you wish to retain the Append qry idea might be more
favorable over the Make table qry.

Okay, now you database gurus...
(1) Are there any other advantages/difierences one over the other?; and
(2) What about database size impacts. grow/shrink, assuming the amount of
data is fairly consistent from time to time of run?

 

[Jeff Boyce]

JOPO (just one person's opinion)...

Having a "known" structure (i.e., using the Append route) means all your
queries, procedures, reports, forms, relationships, ... can be set up and
left in place.

Using a Make table means starting over (many times), and will mess with your
relationships among tables.

It would help us help you more if we had some context for this decision.
Are you saying that you have something new each time, removing the
possibility of reusing (i.e., Append)? Or is the data actually going to be
used for updating ... that is, do you actually have to wipe out the "old"
version before loading in the new data?

More info, please...

--

Regards

Jeff Boyce
Microsoft Access MVP

Disclaimer: This author may have received products and services mentioned in
this post. Mention and/or description of a product or service herein does
not constitute endorsement thereof.

Any code or pseudocode included in this post is offered "as is", with no
guarantee as to suitability.

You can thank the FTC of the USA for making this disclaimer
possible/necessary.

 

[Jerry Whittle]

The Make Table query could cause bloat problems if you are doing it
frequently and/or moving over a lot of records.

The Make Table query will not have things like a Primary Key and indexes.
With an Append query, you already have the table set up.

 

[James A. Fortune]

I am working on updates to a couple related databases (not linked by any
tables) and have a question about virtues of Make Table vs Append queries..

Make Table:  I understand that this will create a NEW table where ever it is
pointed,
                   so if that table already exists inthe destination it
will be deleted, and
                   the new table written in its place..

Append      : In this case I understand that it would require a little more
"work" to
                   do same as Make Table, i.e. clearing out table before
appending data.

The 1st major difference, other than additional steps, I can see is if you
have a table structure you wish to retain the Append qry idea might be more
favorable over the Make table qry.

Okay, now you database gurus...
  (1)  Are there any other advantages/difierences one over the other?; and
  (2)  What about database size impacts. grow/shrink, assuming the amount of
data is fairly consistent from time to time of run?

"MJ",

Barring relationships, here's not a huge difference between using a
Make Table query and using an Append Query after a Delete Query. If
you use the Make Table query and have no relationships, you have to
add things like indices afterwards either by hand, through VBA or
through DDL, as well as running the Delete Query first (most cases);
and you're really gonna want those indices if the resulting table is
going to be joined with other tables. If you use an Append Query it
would be good to check that the table you're appending to exists. If
relationships exist, I'd say that swings the advantage to Append
Queries after running Delete Queries. One drawback with that
combination is that you should make sure that the Delete Query
finishes before starting the Append Query (perhaps by using
MyDB.RecordsAffected after a MyDB.Execute strSQL, dbFailOnError). If
the amount of data to be appended is large, you might want to put the
table in a separate .mdb file if you don't need to maintain
relationships, or keep the table in the backend and compact it
occasionally to remove bloat if you do need to maintain
relationships. The query plan shouldn't change much if the amount of
data is anywhere near consistent.

James A. Fortune
(e-mail address removed)

 

[Marshall Barton]

I am working on updates to a couple related databases (not linked by any
tables) and have a question about virtues of Make Table vs Append queries.

Make Table: I understand that this will create a NEW table where ever it is
pointed,
so if that table already exists in the destination it
will be deleted, and
the new table written in its place.

Append : In this case I understand that it would require a little more
"work" to
do same as Make Table, i.e. clearing out table before
appending data.

The 1st major difference, other than additional steps, I can see is if you
have a table structure you wish to retain the Append qry idea might be more
favorable over the Make table qry.

Okay, now you database gurus...
(1) Are there any other advantages/difierences one over the other?; and
(2) What about database size impacts. grow/shrink, assuming the amount of
data is fairly consistent from time to time of run?

Creating and deleting a tabledef object is more expensive
(time and space) than just deleting and adding records. The
space used by the deleted records can often be reused, but
the space for the tabledef object is more difficult to
cleanup. Bottom line, make table queries should be avoided
whenever possible.

If you really have to use a temporary (will be deleted and
recreated) table, then it is strongly recommended that you
use a temporary mdb file to contain the table. This may or
may not simplify the code, but it definitely avoids bloating
your real mdb file (and dramatically reduces the need to use
Compact).

 

[Al Campagna]

MJ,
Make Table query vs. Append query is like a saw vs. a hammer.
They are two unique tools. So there's really no way to determine
"advantages/disadvantages" between the two. One is great for cutting
boards, and one is great at pounding nails... :-D

Make Table does create a "new" table, but only replaces an exisiting
table if the table name is the same.

Append is meant to add records to an "existing" table. While it might
be used to "act like a Make Table" (ex. two actions - delete all the records
in an exisiting table, and then "append" records to that empty table),
there's really no need to do so when Make Table does the job in one action.

Database size/growth is dependent on many factors.
Indexes, linked Images, record deletions, table deletions, editing,
etc.. etc... all contribute to DB growth.
Regular backing up and Compacting is essential to keep your DB slimmed
down.
--
hth
Al Campagna
Microsoft Access MVP 2007-2009
http://home.comcast.net/~cccsolutions/index.html

"Find a job that you love... and you'll never work a day in your life."

 

[vanderghast]

And in a split design, the front end part is sometimes a nice place to
create that temporary table, without interference from other users.


Vanderghast, Access MVP

 

[Al Campagna]

To all,
The points about the realtionships and key fields remaining intact
is a point I did not consider.
That is a definite advantage/diference between Make and Append.
Excellent point! Thanks...
Al

MJ,
Make Table query vs. Append query is like a saw vs. a hammer.
They are two unique tools. So there's really no way to determine
"advantages/disadvantages" between the two. One is great for cutting
boards, and one is great at pounding nails... :-D

Make Table does create a "new" table, but only replaces an exisiting
table if the table name is the same.

Append is meant to add records to an "existing" table. While it might
be used to "act like a Make Table" (ex. two actions - delete all the
records
in an exisiting table, and then "append" records to that empty table),
there's really no need to do so when Make Table does the job in one
action.

Database size/growth is dependent on many factors.
Indexes, linked Images, record deletions, table deletions, editing,
etc.. etc... all contribute to DB growth.
Regular backing up and Compacting is essential to keep your DB slimmed
down.
--
hth
Al Campagna
Microsoft Access MVP 2007-2009
http://home.comcast.net/~cccsolutions/index.html

"Find a job that you love... and you'll never work a day in your life."

 

[John W. Vinson]

I am working on updates to a couple related databases (not linked by any
tables) and have a question about virtues of Make Table vs Append queries.

Make Table: I understand that this will create a NEW table where ever it is
pointed,
so if that table already exists in the destination it
will be deleted, and
the new table written in its place.

Actually, you'll get an error message and it won't make the table.

Append : In this case I understand that it would require a little more
"work" to
do same as Make Table, i.e. clearing out table before
appending data.

The 1st major difference, other than additional steps, I can see is if you
have a table structure you wish to retain the Append qry idea might be more
favorable over the Make table qry.

Okay, now you database gurus...
(1) Are there any other advantages/difierences one over the other?; and
(2) What about database size impacts. grow/shrink, assuming the amount of
data is fairly consistent from time to time of run?

I very rarely find MakeTable queries either necessary or appropriate. The one
case would be in those (rare but real) cases where a temporary table is
needed; I'll generally use the CreateDatabase() method to create a new backend
database, and make the table in that; I can then delete the .mdb file that was
created when I'm done with it, so as not to cause bloat in my production
database.

Append queries to an existing table have the benefit that the table can have
the desired datatypes, field sizes, relationships, indexes all in place.
Running a DELETE * FROM Scratchpad; query is easier than doing all of that
every time!