Saturday, March 9, 2013

A2b–Database–Grading Comments

Overall Comment

This assignment went quite well overall, with most of you understanding and appreciating the purpose.  Below I’ve addressed several issues that came up repeatedly

Planning

  • Many of you realized the value of what Dr. Song emphasized, the importance of planning your database design in advance.  It’s just like a building – adding an elevator after the fact is MUCH harder than in the design stage.

Using Record ID Fields

  • In my comments I referred a number of you to a post I thought I’d made (but now cannot find) about common problems with the first database assignment.  This had to do with the frustration that Access automatically assigns a number to a field that is identified as a “primary key”.  Using a primary key value for a particular record can thus be a problem if you delete it and think you’re recreating it – there’s a new primary key number which is NOT what you had before.  The trick is to not delete and recreate the same record OR do not use primary keys in “drop downs”, but instead use a descriptive field.

How To Enter Records Without Having to Look Up their key field.

  • Access provides a method, one of number of “controls”, to produce a dropdown box in a form.  You can then see the value of a descriptive field in the dropdown menu, but Access actually puts the value of its primary key in the field.
  • One or two of you experimented with this successfully.

Other Databases

  • As I’d hoped, a number of you claimed to be quite interested in using Access further.  You should be aware that “serious” database people tend to sneer at Access (unjustly I’d say).  The fundamental problem is that large databases need to be used by many people simultaneously.  Access is not good at this.  If that’s what you need then you’re into the world of either a web-based database (probably PHP and SQL)  or a commercial product like those from Oracle.  These get more complex than Access quite quickly.
  • Several saving graces are:
    • the principles you’ve learned using Access still apply
    • The SQL language that underlies Access is used throughout the relational database world.
    • You can actually connect to large SQL databases using Access.

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