Re: Different MSSQL output date format from the same PHP script

Willem Bogaerts wrote:
Please don't delete attributions; they're important to following the
conversation. I've readded them.

Then please read them and don't turn things the other way.

SELECT * is not a good thing to use. You are much better off always
specifying the columns.

For one thing, it's very seldom you need all of the columns.
Why put columns in a table if you are not interested in them? It is
really rare and a sign of bad datase stucture if a table contains things
I do not want to select.
This is a strawman. Jerry suggested no such thing. He said that you
don't usually need all of the columns for a particular query. IME
that's quite true.

As I indicated, this is not true for my way of programming. It may be
very well true for yours. But that does not make "SELECT *" bad in all
case. THAT is what Jerry suggested. By the way, this thread was about
dates in queries of that type. Just saying it is bad does not help.
Especially when "SELECT *" queries just do have their uses.


Yes, it is what I suggested. Just because it's "your way of programming" does not make it good.

The only time I want all fields from a particular
table is usually when allowing record additions and editing via a user
interface. Even in those cases I generally use views because I'm
joining against related tables. Most of time when I'm querying,
however, is for reporting, which usually requires only a subset of the
available columns.

And that is excatly the opposite for most of my programs. My programs
are object oriented, and an object usually "maps" to a row in a
database. If my application evolves, so do both the table and the
object. This is where ORM and "SELECT *" queries are of great value.


Not in my experience. It is exactly the way most programmers I've seen do it. Not necessarily views, but obtaining only a subset of the available columns.

And the fact your programs and databases evolve makes it even more important to specify column names.

I do a lot of OO programming, also. And I never use SELECT *, and very seldom am selecting all columns in a row.

The fact you need to do this regularly is an indication that you may be overnormalizing your database.

So instead of telling that the original poster is wrong, people may
actually consider helping him.


We are trying to help him. Because it is a poor programming practice.

But more importantly, what happens if someone later adds a new
column to the table (i.e. a 5mb BLOB)?
Well, first of all, that would be me.
Are you the only one who ever works on the databases you create? If
so, do you think that your experience is representative?

Yes. As I told above, that is the mere structure of the application. My
programs "depersist objects" far more often than they "report data".


So you are the only one who works on those databases? And your experience is representative of the industry?

If I would add such a column, I would have a need for it.
In every single case that you wanted to retrieve data from that table?
You wouldn't want to ever want to, say, run a query returning all
unique authors associated with the documents that are in the BLOB
field?

No, off course not. I did not say that I NEVER used field names, did I?
For searching and reporting, I still use complex JOINs, a subset of
field names, etc. It just so happens that those queries are less than 5%
of my application. That may very well be the opposite for yours, but I
will not tell that to be bad and stop responding to a perfectly normal
question.


You may think it's not bad, but many other, more experienced programmers will tell you it is. In fact, in my programs, SELECT * is in zero percent of my queries. That's what virtually all good SQL programmers recommend - and have been for years.

If that field would only be vaguely connected to the rows in that
table, it would be in an only vaguely connected table.
Sorry, but this doesn't make any sense to me.

If the field would not really be part of the entity that that row (and
that object) represents, it would just not be in that table.

An example:
Suppose the table is a table with images. If I want to retrieve the
image object, I would need the image ("SELECT *"). If I wanted to search
which objects I would want to read, I would use different queries or
already have IDs in other objects. If I wanted to do both, I could
combine them.


I agree with Charles - this makes no sense to me, either.

So what happens? I would update the mapping table and a template and I
would have an extra field on my web form. Without the need to modify the
code. That is why ORM layers exist, is it not?

Also, if someone later deletes or renames a current column, the query
will fail, making the problem very obvious.
On the contrary, "SELECT *" will NOT fail.
He meant that if you write your query as "SELECT FirstName, LastName
FROM employees" and someone renamed "FirstName" to "GivenName", then
the query will fail immediately. SELECT * will not. Whether using
SELECT * will cause problems depends on whether your code references
"FirstName" by name.

So? The query itself may not fail, but the rest of my code (most
probably the ORM section first) will. Just as immediate. What's the
difference?

Regards,

The difference is the query is now the point of failure. That's the closest to the actual error. The farther you get from the error, the harder it is to troubleshoot, and the more time it takes to correct.

I really suggest you ask about SELECT * in comp.databases.mysql. The experts there will also tell you why it's bad to use.

--
==================
Remove the "x" from my email address
Jerry Stuckle
JDS Computer Training Corp.
jstucklex@xxxxxxxxxxxxx
==================

.

Relevant Pages

  • Re: merge multiple databases
    ... Well, as YYZ said, I myself tried built in queries in the Access database ... databases, I need to do everything through DAO. ... I ended up> with an internal Access Make Table query and then a> ton of update queries. ...
    (microsoft.public.vb.general.discussion)
  • Re: merge multiple databases
    ... Well, as YYZ said, I myself tried built in queries in the Access database ... databases, I need to do everything through DAO. ... I ended up> with an internal Access Make Table query and then a> ton of update queries. ...
    (microsoft.public.access.queries)
  • Re: merge multiple databases
    ... Well, as YYZ said, I myself tried built in queries in the Access database ... databases, I need to do everything through DAO. ... I ended up> with an internal Access Make Table query and then a> ton of update queries. ...
    (microsoft.public.vb.database.dao)
  • Re: Please Help with database upate. New to database
    ... new to databases and doing alot of reading and OJT. ... search that master query. ... could be queries as long as I can export that data into excel. ... FROM tblA LEFT JOIN tblB ON tblA.Field1=tblB.Field2 ...
    (comp.databases.ms-access)
  • Re: calculations in forms vs queries?
    ... query work is more difficult for most programmers, ... So, for most, doing calculations in a control is preferable. ... For those who are more advanced in query writing, ... Rather complex queries ...
    (microsoft.public.access.queries)