(By Ian Andrew from Canberra with a little bit of help from Garry Robinson.)
Setting the Scene
we took on an elderly, undocumented Access 97 database linked to a MySQL back-end.
The task was to fix existing problems, upgrade to Access 2007 and Vista, and bring the functionality in line with current
business practices. It would involve an independent re-build (mainly off site)
so that existing operations could continue unhindered.
changes werent ideal: when a problem arose, we had to work out whether it was
due to a flaw in the original database, or 97 to 2007 differences, or some
aspect of the Access to ODBC driver to MySQL linkage. But we had no choice and
with Allen Brownes comprehensive list of Access 2007 issues, we marched on.
completely new to us. Moreover, while we knew an updated back-end would be
needed, we didnt know whether it should remain MySQL or change to Access. So
we wanted to keep both options open.
An early problem,
before we could start work off-site, was that there were two sorts of links
from the front-end to MySQL tables. In the first case, the tables were linked
via the MySQL ODBC driver: we could re-link to the development back-end and queries,
forms/reports and VBA references continued to function. In the second case,
pass through queries and ADO connections referred directly to the
on-site MySQL server and database: these would not work off-site. To simplify
matters, the latter were changed to normal queries and DAO references to the
Finding Out About MySQL
Our aim was
to set up an off-site copy of the working MySQL database, an Access version of
the same back-end, and a front-end that could link to either.
So how to
do it. We started with Google. MS Access and MySQL found a range of
references: a non-exhaustive list of tools and advice we found useful follows:
Most of the
advice was from a MySQL point of view, but we found these all worth reading.
On with the Story
As its unlikely youll find yourself in
our situation, for the rest of this narrative well assume you are an Access
developer who wants to migrate an Access back-end to a local MySQL server for
development and testing purposes. Youll maintain your own solution and are
happy to use the Community Server (free).
Step 1 Install MySQL
Go to http://dev.mysql.com/downloads/ to download
the server, MySQL GUI tools and MySQL ODBC driver. You have a choice of server:
5.0, 5.1 or 6.0 (Alpha). Weve used 5.1 and 6.0 without any problems. Then
install all three.
Points to note during installation:
Your firewall will have to be set to allow
connections through Port 3306.
We chose to run MySQL as a service (command line
is an option).
MySQL installation defaults to username/login = root
and server = localhost.
MySQL offers a choice of storage engine/table
type the main ones are MySAM or InnoDb. The latter seems more like Access,
with transactions and foreign keys, so at the moment were leaning that way.
User and security options are available. Dont
forget to record any passwords.
We also installed Bullzip Access to MySQL
and Dreamcoder for later use.
Step 2 Move Tables from Access to MySQL
Either use Bullzip to transfer back-end
tables to MySQL, or open your database and export the table via ODBC.
Points to note:
MySQL does not recognise Access functions used
as field defaults (eg Now() and Date() in Date/Time
fields): they may be dropped or the table rejected. Recommend you remove them
Access autonumber fields are not identical
to MySQL auto_increment. Bullzip will
convert on transfer, ODBC will not.
Access data types will be converted to similar
MySQL data types. However, there is a greater range in MySQL (refer to the
Manual) and you may wish to change them later.
An Access ole object becomes a blob in MySQL. Due to an OLE Server problem, we changed blobs to longtext
(memo in Access).
Step 3 Modify MySQL Tables (Columns)
Open Dreamcoder (easier to use at this
stage) or MySQL Administrator (one of the GUI tools). If you are used to SQL
Server, think of these as the Enterprise or SQL server management studio express interfaces.
Connect to the transferred/exported
Figure 1. Dreamcoder Database Connect
Open each table in turn and check:
autonumber fields(columns) are auto_increment.
There is a primary key (one or more fields) for
each table (in Dreamcoder, Create New Constraint). Otherwise, youll
have to nominate when linking and/or the linked table will not be updateable.
Field defaults are correct. We checked for
consistency with front-end data entry defaults.
should be allowed or not.
Data types are as desired.
There is a timestamp field with default current_time (usually the last
field in the table).
Figure 2. Edit Tables
Step 4 Setup Your MySQL Backup Systems
Open MySQL Administrator and back up your
MySQL database. This will save the schema and data to a .sql file. If you want
to set up the database on another computer, install a MySQL server on that
machine then restore a copy of the .sql file to the new server.
Figure 3. Backup MySQL
Step 5 Link Front-End to MySQL
Open your Access front-end. If you are
already linked to an Access backend, you cant use the linked table manager to
change to an ODBC data source. So delete the links to the Access backend and
link, via ODBC, to the MySQL back-end. Similarly, once linked to an ODBC data
source, the linked table manager offers only a choice of ODBC sources.
When setting up the ODBC data source, in
ODBC Configure Advanced Flags1, tick Return Matching Rows and Allow
Figure 4. ODBC Data Source
Observations so far:
Access 97 with a MySQL backend was significantly
faster than Access 2007 with the same backend.
The original combo and list box row sources used
the row source query builder. For some reason replacing them with user-created
queries improved speed dramatically.
In the current configuration, Access 2007 with
an Access backend is a little faster than with the MySQL backend.
Our next step is to test the effect on
performance of using Access pass through queries and MySQL queries (views).
Questions and Answers
Did you need any special skills to
work with MySQL?
No. Access developer experience plus the
MySQL information available online and from the Manual was more than enough to
get us started on this migration project. If we go beyond small-business use,
no doubt well be attending MySQL training sessions.
Why migrate to MySQL?
Listed benefits include:
Scalability (not subject to Accesss 2GB limit).
Heavy duty multiple user capability.
Security (secure password and privilege system).
Portability (Windows, Linux,
) for your back-end
Connectivity (Access front-end, or accessible
over the Web using a range of client programs). Note that you had better
discuss security with a web professional before doing this.
Why stick with Access?
Easier to develop and maintain because you only
need to know the one tool.
The client was happy with his MySQL back-end
and weve been able to re-develop it for him.
At its current size an Access backend
also would be suitable, but there is no major benefit to be gained by
We have learnt a new server/database
system that may be useful in developing future applications.
About my colleague
Ian Andrew is developer from NSW in Australia that has been helping me out for
the last two years. In that time, Ian has worked with airlines, mining
companies and a qualitative research firm and has racked up good Access solutions
that are easy to use.
See All Articles by Columnist Garry Robinson