ebmigue
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Posts posted by ebmigue
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4NF, 5NF, BCNF, and often even 3NF is not necessary for working with real-world data.
State your reliable basis/reference for saying that. Things as crucial as this should not be based on mere baseless opinion.
Opinion, yes -- baseless, no.
Besides, why will you acccept someone else's opinion as a "reference", but not mine?
What is the basis then? Please post here.
I accepted theirs, because they have their basis. Their basis's basis also has their basis - w/c brings them back again to the leading authors.
Why accept the views of the leading authors? No, you just don't accept it. We have to examine it too. That's why we need your basis. Your reasons, in detail.
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I'd suggest that you use re (http://www.reetudes.com).
I have no problem with you suggesting the use of a library you've obviously put a lot of time and thought into, but I think you should make it really clear that it's your library. For example: "You might consider my library: for these reasons....". vs. suggesting it in a thread like this. Yes it could be inferred from the link in your signature, but I think you need to come right out and state it, whenever you are suggesting people use it, or risk the appearance that you're not being entirely forthcoming about the potential for bias.
Noted.
I thought that stating it explicitly that is is "my library" would be a bit immodest.
I would like to give the impression that it is a library that is for everyone, and could be modified by anyone (it's released as a FOSS).
Hence the avoidance of the term "my library."
I will try to improve my phrasing on the next opportunity.
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@OP
Enumerate the fields/attributes of each view that you want JOINed.
Enumerate the fields/attributes of the resulting JOINed views.
Tell us about the candidate keys of each views, and the resulting view.
Tell us about the criteria/predicate in your WHERE clause.
Most of the time, posting the actual source-code of views is not helpful since it will just produce confusion and too much information.
From a conceptual perspective the attributes of the views/table and result in question would suffice (w/ the their keys of course.)
Thank you and hope it helps.
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Thank you. You just learned, because I told you not to do something, and then you didn't do it. I had to say it twice, but I don't think I gave you any theory.
To save time, and to end this senseless bickerings with you, I will reply to your posts only if you provide us
your sources/references/materials that will help us with "erline tables," w/c will hopefully shed light on the discussion about NULL.
Otherwise, replies to your posts will be fruitless and ill-conceived.
Thank you.
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There it is again. Blurting nonsense. We are adults here. Let us be.
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Why is it depressing to suggest that visionaries are too busy to deal with mundane, day-to-day tasks?
Men of science are not visionaries, like the "prophets." They deal with very real scientific problems.
Why do you think that not working out the proof, or taking advantage of an edge case that breaks the rules of a theory, detracts in any way from the theory itself? That's like suggesting that using special relativity is an insult to general relativity.
Such can not be inferred from my posts.
It's not -- it's easier, and that why we use it. Approximations are useful. So are hacks, workarounds, short-cuts, and hard-coding. Real-world solutions to real-world problems. Academia isn't subject to those constraints.
Yes. Hacks, approximations, work-arounds are useful. No question. But only if the instances on w/c they are applied are still the state-of-affairs. Fix a certain bug, and the workaround goes away. Refine an implementation, and the hack becomes needless.
Implement a certain DBMS according to the principles of the underlying theory it professes it implements - in this case Relational Theory - then all those things goes away.
The unacceptable thing is that a certain DBMS labels itself "relational" where in fact it is not; it is a network model; or "table" model. That's misleading people.
We should start calling things as they are; and implement things as it should be.
It is not an easy task of course. Unintelligent replies makes it harder even more.
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In theory, you should quote every post to which you reply. In practice, you're rediculous to do so. Look at what you just did. You repeated the entire previous post. That's literally retarded.
And someone can give you step by step directions on how to do something, without giving you any theory at all. In case of fire, break glass. Push the button to start the tractor.
In fact, I'd argue that all safety-instructions are done with zero safety. In case of emergency, dial 9-1-1.
No why, no how, no if, on because. Just do it. And buy my shoes. It works for marketing too.
All right.
Completely irrelevant to the discussion. And somewhat ridiculous.
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4NF, 5NF, BCNF, and often even 3NF is not necessary for working with real-world data.
State your reliable basis/reference for saying that. Things as crucial as this should not be based on mere baseless opinion.
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@fenway
I have no say to your professional opinions/decisions.
If you undermine the importance of theory, of the basis of your technology (for technology is applied science, and science is theory) - if you forget that basis, well, I cannot anymore do anything.
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Sure -- but I'm not trying to judge it at all. I'm trying to help people USE it. That's where "ephemeral" knowledge becomes vitally important.
Let me be clear.
Think of a calculator. Can you really use it w/o knowledge in arithmetic?
Of course not. W/o such knowledge all you can do with the calculator is type silly words.
You can -- if someone else shows you how to use it correctly.
How will they show you the correct way? Only if they use theory. That's how.
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Actually, what you want could not be achieved by a LEFT JOIN (w/o using a subquery)!
Ah, I will correct that. This can be achieved using LEFT JOIN and NULL, as fenway suggested above.
Sorry for the wrong info.
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You've said that without Google, you can't figure what something is. I could tell you that I mis-spelled it, or I could tell you that there's more to knowledge than Google. Perhaps you could ask a human being, and do some actual research on your own -- some real research, not just a search engine. But in the end, this is the great example of your worldly understanding. You don't know what something is, and you don't know where to find out, and you can't think of where to look beyond Google.
Oh, come on, man. Don't be like that. I'm sorry if I didn't fare well with google. So can you state the name of the author/proponents of the "erline table"? I am genuinely interested in learning about it. Please?
Now, back to your calculator. Ever use your calculator for trigonometry? Ever ask for the sine or cosine of an angle? Ever wonder how the calculator gives you that answer? I bet you'd be amazed at how your calculator calculates the cosine of 63 degrees. And since trigonometry was done long before calculators, I'll bet that you'd be stupified as to how trigonometry was done a few hundred years ago.
Can't understand, and non-analogous.
I didn't refer to the "cost of your advice" -- that's free because it's not worth much more. I referred to "the cost of what you advise". Learn the difference. Read the sentence as many times as you must. It's English, and small words at that, so I will not rephrase it.
I am advising others to learn theory, to avoid mistakes. There is no guarantee however that you will not be mistaken if you knew theory. So why learn theory? That is for you to answer.
You most definitely came here to share and talk about useful ideas. You did not come here to apply those, nor inspire others to develop their own -- which is why you've managed to goad me into talking and sharing with you, and not into actually presenting useful code to others.
I didn't offer code because I think the OP is already satisfied with what others had given. Or perhaps he solved it on his own.
There are benefits to not understanding something that have nothing to do with making errors. Not understanding something allows you to be free of repeating the same, shall we say inefficiencies. Yes I am a pioneer in my field. I entered a perfectly good existing field, and chose to make it better in a certain direction, because I saw it missing in others' interpretation of the same field. Had I known why they did what they did (and still do), then I would not have been capable of guiding my own path. If you ever choose to follow your own path, you'll discover that the benefits are no where near the beginning, and you never end up where you thought you'd be. But you end up in a place that no one ever knew could exist. And that's the pioneering part.
I don't believe in school -- the word is an accurate description of the process, which has zero educational context. And school is free around here, so I'd save zero money by not sending my children to school (I don't own any young goats, by the way.). But I never said that being taught by teachers and then ignoring them isn't a good thing. In fact, if you read through my general context again, you'll note the opposite. There's a skill to being able to ignore dumbass information, the repeated mistakes of others, the delusions followed by the masses, and the over-simplifications that come from incomplete tutorials. Just as well, there are skills to be learned in verifying what's been taught to you, which parts are useful, and how you can be inspired to take things further, farther, or turn things around. Those are the skills to be learned in school -- those, and how to become immune to illnesses that thrive in the enclosed proximities of indoor populations.
So why waste my time telling you things that you might not understand? I think I've answered that question.
I did not understand those string of words. Sorry.
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Ok, so you have no idea what an erline table is. I guess it would sound like nonsense to you. But that's very consistent with the majority of your arguments.
I've googled "erline" and not found any significant results. That's my "basis" for dismissing it as nonsense. Perhaps you could share your references to me, to us?
So I'm disappointed, but not surprised.
Your disappointment and surprise are of no relevance to me. So why state it?
You're just totally wrong when you say that you need to effectively use something to have the value of using it.
What is your basis for saying that? Ah, the erline table. Is my example/analogy on calculators not clear enough?
You've completely ignored the costs associated with acquiring formal knowledge of any given device. For the number of defective calculators out there, that formal knowledge is way to high of a cost to cover the few defective calculators.
I have not understood what you meant or imply by that string of words. Please clarify.
You, like so many others, completely disregard the costs of what you advise. That's irresponsible.
I am aware of the "cost" of my advice. It's free.
If "my advice" means undervaluing existing DBMS, so be it. I have the backing of the leading authors. Certainly, I have no personal acquaintance w/ them but I had given the links to where you could read their papers.
But since you don't actually do anything with your knowledge, it's not surprising that you don't see its cost.
I'm not doing anything w/ my knowledge? Wow. What do you call this? I am sharing it. But many people may not be comfortable it.
I don't care. I have nothing personal against them. I came here to share and talk about useful ideas, not about emotions and preferences of people.
You also lose out on all of the benefits that can be gained by specifically not understanding how a device works; there are many, and most of them surround not only speed but innovation.
Of course, experience is the best teacher. If you created a device 99 times wrong, 1 time right, the 99 times you failed is valuable in-itself. But that is if you don't have existing theory - if you are a pioneer in your field of invention. Are you the pioneer? No you're not.
So basically, you're slow, uninspiring, and completely text-book about everything. Which means that you should teach; and then your students should ignore you.
Maybe I am. So why waste your time telling me things that I might not understand, since, I am a very boring and dull person?
Again, why send your kids to school, if in the real world you are telling people to ignore their teachers? How can you live with that? I am interested in knowing. Save your money by not sending them to school.
But that's typical of most in your position. So good luck.
That could apply to you, too.
Thank you for wishing me luck, though.
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Sure -- but I'm not trying to judge it at all. I'm trying to help people USE it. That's where "ephemeral" knowledge becomes vitally important.
Let me be clear.
Think of a calculator. Can you really use it w/o knowledge in arithmetic?
Of course not. W/o such knowledge all you can do with the calculator is type silly words.
The same thing for a DBMS. The DBMS is a calculator - a very powerful, complex calculator. Its input are not only numbers, but, primarily, sets.
Now, can you use it w/o knowledge of set-theory, of relational theory? No, sir, you cannot.
Imagine a kid who has no knowledge of arithmetic. Then his lazy math teacher gives him a defective calculator. And the teacher says, "this device will perform addition for you. Just type the numbers." And when the kid does input 2 + 2, it gives 5.
Now he goes on telling the world that he knows addition by heart. He does 2 + 2 = 5.
What's wrong with the story?
He didn't know arithmetic. That's what's wrong with it. He didn't bother checking his calculator. How can he check his calculator - how can he evaluate its effectiveness or defectiveness? Knowledge about theory. That is the only way.
To be sure, yes, you can use a DBMS w/o formal knowledge. Relational theory also relies on intuition (as mathematics and logic do) - we can know it "by nature" so to speak.
But if you want to effectively use it - and not just use it - you have to do more than intuition.
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MIT is full of people who don't know how to program computers for day-to-day real-world scenarios -- that's not their job. Their job is to solve problems we're going to have 50 years from now, not program silly websites.
That is a depressing opinion, considering that most users here are web programmers. Also depressing for folks there since what you said implied that they are useless (at least now).
Trust me, I've taken those computer science courses when algorithms needed formal proofs -- sure, it's a great mental exercise, but nothing more.
Again, you are degrading useful knowledge. You are practically saying that Pythagoras's theorem was "just a mental exercise - nothing more." A typical preposterous opinion.
Sure we don't need formal proofs everyday. Someone already, most likely, took care of it for us. But without that someone, we can never be sure of what we are doing.
We owe the reliability of the enterprise of computer programming to them, whether you recognise it or not.
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@fenway
Taking DB normalization to it's logic end is often overkill.
Please refer us to your basis for saying that. Otherwise, you are misleading people -- and that is irresponsible.
@OP
Actually, no one can help you w/ regards to database design but the science of db normalization, your knowledge of the requirements, and some amount of experience (or intuition as some would call it).
All we can do is suggest. There is hardly a "right" suggestion. You alone will determine it, if it is within your requirements. And the science of db normalization is usually a helpful guide in achieving your requirements.
I'm saying this because you might get the impression that we are giving "absolute answers." Just to be sure, so that I won't run risk of misleading you.
Hope it helps.
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No, their responsibility is to provide a product that works in a consistent fashion with predictable output.
Now, is their product like that? No, I would claim, with theory as my guide.
Since you're not paying for it (presumably), you can't demand anything of them.
Yeah I know. But you have to wonder why people are actually paying it.
The point is, I'll start paying them, when the product is already right. Hence, my criticisms.
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To me (with limited experience) this makes perfect sense to me:
SELECT * FROM main_table a WHERE NOT EXISTS( SELECT * FROM some_table b WHERE a.id = b.id)
Can you show what the left join null code would look like? I would like to see the "correct" way (or "parser way" as you guys were saying)..
What you really wanted is the SEMIMINUS relational operator. That operator is neglected by MySQL, and thus the different "workarounds" being suggested here.
Actually, what you want could not be achieved by a LEFT JOIN (w/o using a subquery)!
And using a subquery, in general, in today's state-of-affairs is generally non-optimal.
Someone can suggest to you the LEFT JOIN version of course, but it pays to research it on your own. =)
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@fenway
Sure -- but I'm not trying to judge it at all. I'm trying to help people USE it. That's where "ephemeral" knowledge becomes vitally important.
Oh. I thought if you want to learn to drive, surely you must have a working car. You need not know mechanics. But at least you must have some basic idea - your judgement - about the car in question. Otherwise, "using" the car becomes a ridiculous enterprise.
I will not deny that implementation issues are important. They are vital as theory. They may be ephemeral, but they are still vital.
But: IMO, people do not care anymore about theory. They always concern themselves with implementation, with product-specific facts and quirks.
They do not anymore question the product itself. They treat the product as the last say about relational theory, where in fact there is still more; and that the community, aided with theory, could pressure the leading vendors - the ones with great resources - to create a more stable, useful, theoretically-sound product.
That's the whole point.
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@holophrastic
You know what an erline table it, or you wouldn't think it irrelevant. They fly in the face of your theory concept, as they are nothing more than real-world look-up tables derived purely from observational experience, summarizing data that can't be predicted from any known algorithm.
And certainly, we don't ever want to "judge the usefulness" of anything. We want to demonstrate the usefulness. Two very different things.
Stop blurting nonsense, please.
But we left on-topic long ago.
I may agree on this. But at least what we are discussing was not nonsense.
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I was confused.
What is it that you worry about? The security of your data? Or the structure or your data?
If security:
you can always try the conventional encryption/decryption functions/operators available in PHP. Or write your own.
If structure:
I suggest you use the relational structure. That is, tables. They are better documented.
Of course, deciding on a structure might involve performance considerations.
But if using an arbitrary structure only has negligible improvement in performance, then using a better-documented structure is more advantageous.
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@OP
Perhaps,
SELECT SUM(IF(increment_day < '2010-06-01',SUM(detail.counts),SUM(detail.clicktositeindicator))) as CTS FROM ( SELECT * FROM vdat_2874 WHERE increment_day >= '2010-06-01' UNION SELECT * FROM vdat_2992 WHERE increment_day <= '2010-06-01' ) detail WHERE campaignid IN (1633605)
will do?
Hope it helps.
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Hi everyone,
Please could somebody give me their views on which is a more efficient and faster way to update multiple rows of a database with different values?
Using a query within a while loop or using a query with a case?
Thanks
Why would you want to use a loop when using SQL UPDATE?
The whole point with SQL UPDATE is not to use loops anymore, because the DBMS will take care of it for you.
Of course, there are cases, that it is necessary to use loops.
But still, use UPDATE, use CASE WHEN in the SET clause if necessary, and refine your WHERE clause. That ought to do it.
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@OP
Did you try what I suggested?
Using stored procedures, and transactions? Or using try catch and transactions?
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Your columns are:
SALES_PD_1, ..., SALES_PD_9, SALES_PD_N
Did you consider normalising this?
Query: retrieve NULL values
in MySQL Help
Posted
Telling us that something exists, where we have evidence of the contrary, will not prove your point.
If you really want us to learn something, teach us about it, by pointing us to the first step.
Otherwise, you are misinforming us.