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Forum: Theory and practice of database design 02-17-2019, 10:42 AM
Replies: 45
Views: 8,536
Posted By ButtonMoon
Re: Meaningless vs Meaningful Primary Keys

Not my phrase. It was used by Mike Smart at the start of this thread. In fact I try to avoid the term "alternate" and I would usually just say composite key. According to Google Books there are 69...
Forum: Theory and practice of database design 02-17-2019, 08:31 AM
Replies: 45
Views: 8,536
Posted By ButtonMoon
Re: Meaningless vs Meaningful Primary Keys

isladogs,

Thanks for correcting my syntax. You are right.



You said you understand the terms alternate and composite. What else would you call a key that is both alternate and composite? Do...
Forum: Theory and practice of database design 02-16-2019, 04:42 AM
Replies: 45
Views: 8,536
Posted By ButtonMoon
Re: Meaningless vs Meaningful Primary Keys

A composite alternate key is just an alternate key that has more than one attribute (nothing to do with foreign keys). For example, this table has two composite keys: (a,b) and (c,d).

CREATE TABLE...
Forum: Theory and practice of database design 02-16-2019, 03:49 AM
Replies: 45
Views: 8,536
Posted By ButtonMoon
Re: Meaningless vs Meaningful Primary Keys

A composite key is a key consisting of more than one attribute. An alternate key is just a key that isn't the "primary" key (alternate keys are sometimes called secondary keys, candidate keys or just...
Forum: Theory and practice of database design 02-15-2019, 07:13 AM
Replies: 45
Views: 8,536
Posted By ButtonMoon
Re: Meaningless vs Meaningful Primary Keys

Where did this myth originate from? It is possible to create composite alternate keys and has been since at least 2003 (and probably before) as far as I know. There are multiple other misconceptions...
Forum: General 11-27-2017, 06:54 AM
Replies: 23
Views: 1,745
Posted By ButtonMoon
Re: Books!

Umm, perhaps the fact that it is a niche product which Microsoft has left in suspended animation for over a decade. In the same period the market-leading products covering some of the same core...
Forum: General 11-27-2017, 06:09 AM
Replies: 22
Views: 1,423
Posted By ButtonMoon
Re: selling your work

It's worth clarifying the difference between selling an application and selling a database. Despite the question that started this thread, I believe this thread has so far only talked about selling...
Forum: Theory and practice of database design 12-18-2016, 07:21 PM
Replies: 27
Views: 3,331
Posted By ButtonMoon
Re: Alternative non Server BackEnd to Jet

A common back end in Jet is not a client-server database. My recommendation is that you use SQL Server, Oracle or PostgreSQL.
Forum: Theory and practice of database design 12-18-2016, 10:16 AM
Replies: 27
Views: 3,331
Posted By ButtonMoon
Re: Alternative non Server BackEnd to Jet

Every database ought to be implemented on a client-server architecture. The technology is ubiquitous, cheap and simple so there isn't much reason to do anything else these days. What is your...
Forum: Forms 08-31-2016, 11:23 AM
Replies: 10
Views: 1,491
Posted By ButtonMoon
Re: lower/upper case in password

Here's a slightly more compact way of doing these comparisons:

If Not password Like "*[0-9]*" Then
err = err + "Password must contain at least one numeric character" + Chr(13)
End If

If...
Forum: SQL Server 08-26-2016, 03:43 AM
Replies: 7
Views: 2,543
Posted By ButtonMoon
Re: Security Access to SQL server

When using SQL Server best practice is to use Windows integrated security. Don't use SQL logins or passwords. You can grant only the permissions needed for each user. They don't need to have the...
Forum: Reports 08-23-2016, 03:52 AM
Replies: 4
Views: 367
Posted By ButtonMoon
Re: Which one - Access Reporting or SQL

The choice of SQL won't necessarily make much difference to the reporting experience. Possibly it will make reporting run quicker but that may be all. The choice of reporting tool is what really...
Forum: Tables 07-07-2016, 09:50 AM
Replies: 29
Views: 1,403
Posted By ButtonMoon
Re: Messaging Databse (deep breath)

Access is not the right tool. How about using a web-based email service?

I can't think of any good reason to develop your own messaging service. No disrespect but if you don't have something else...
Forum: Tables 07-07-2016, 01:08 AM
Replies: 8
Views: 533
Posted By ButtonMoon
Re: Is there a way to change a primary key value

Only if you enable the "Cascade update related fields" option. Tophan needs to enable that option on the relationship. Double-click on the relationship line in the Relationships window to see the...
Forum: Tables 07-05-2016, 07:27 AM
Replies: 32
Views: 2,018
Posted By ButtonMoon
Re: Multiple Primary Keys or Composite Unique Index

Social Security Numbers and their ilk tend to provoke pointless arguments. I try to avoid discussing them for that reason. Same goes for hypothetical keys based on people's names and addresses.
Forum: Tables 07-05-2016, 03:09 AM
Replies: 32
Views: 2,018
Posted By ButtonMoon
Re: Multiple Primary Keys or Composite Unique Index

In what circumstances in the UK would you use NI numbers as an identifier? I believe Tax and Employment are the only scenarios where NI number is commonly used. I can't imagine many companies (if...
Forum: Tables 07-04-2016, 08:18 PM
Replies: 32
Views: 2,018
Posted By ButtonMoon
Re: Multiple Primary Keys or Composite Unique Index

In fact you have to compute Damerau–Levenshtein for each pair of values you want to compare, not just for each field (i.e. it's an "edit distance" function). Galaxiom's point I believe is that strict...
Forum: Theory and practice of database design 07-02-2016, 12:21 PM
Replies: 17
Views: 2,710
Posted By ButtonMoon
Re: Data too large for Access. What next?

There are lots of options: SQL Server, Oracle, MySQL. 75GB is a small database and any SQL DBMS can cope with that size of data without problem. The basics of databases really aren't so difficult so...
Forum: Tables 07-02-2016, 11:15 AM
Replies: 32
Views: 2,018
Posted By ButtonMoon
Re: Multiple Primary Keys or Composite Unique Index

The idea of identifying customers by name and date of birth seems to me far too unrealistic to be worth considering. What kind of business would want to ask their customers for their date of birth?...
Forum: Forms 06-06-2016, 04:41 AM
Replies: 25
Views: 1,227
Posted By ButtonMoon
Re: prevent Dublicate ID by Date()

Be sure to make (EmployeeID, barwar) a key if appropriate. Uniqueness in general should be enforced through a unique constraint/index and not just in a form. There's no harm in adding an extra check...
Forum: Theory and practice of database design 06-02-2016, 09:50 AM
Replies: 12
Views: 1,763
Posted By ButtonMoon
Re: FAQ article on nulls needs correction

As I already stated more than once, my "fixation" is not on null sets vs. empty sets at all but on null vs. empty sets. In Access or in any SQL-based database they are not the same thing and don't...
Forum: Theory and practice of database design 06-01-2016, 12:03 PM
Replies: 12
Views: 1,763
Posted By ButtonMoon
Re: FAQ article on nulls needs correction

Are you really saying that you reject the Closed World Assumption - keystone of the relational model and SQL?

Under the CWA, given the following query:

SELECT age FROM employees WHERE empname =...
Forum: Theory and practice of database design 06-01-2016, 01:28 AM
Replies: 12
Views: 1,763
Posted By ButtonMoon
Re: FAQ article on nulls needs correction

I think you are looking for something complicated in something that is very simple:

CREATE TABLE t1 (x INT);
INSERT INTO t1 VALUES (NULL);

Now try the following two queries:

SELECT * FROM...
Forum: Tables 05-30-2016, 12:03 PM
Replies: 29
Views: 1,662
Posted By ButtonMoon
Re: Second Normal Form a Massive Table

The actual question doesn't seem to have anything to do with the title of the thread. And 15000 rows is not really massive is it?
Forum: Theory and practice of database design 05-29-2016, 04:35 AM
Replies: 12
Views: 1,763
Posted By ButtonMoon
FAQ article on nulls needs correction

I have commented on this FAQ article (http://www.access-programmers.co.uk/forums/showthread.php?t=131593) by The_Doc_Man before. Unfortunately I just came across another reference to it and so I'm...
Showing results 1 to 25 of 303

 
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