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Our SQL interview questions

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Re: Our SQL interview questions

#131

Post by codegeek »

pluies wrote: post #124
codegeek wrote: post #44

"List employees (names) who have a bigger salary than their boss" SELECT e1.Name FROM Employees e1 LEFT OUTER JOIN Employees e2 ON (e1.BossID = e2.EmployeeID) WHERE e1.Salary > e2.Salary "List departments that have less than 3 people in it" SELECT d.Name, COUNT(e.EmployeeID) FROM Department d LEFT OUTER JOIN Employees e ON (d.DepartmentID = e.DepartmentID) GROUP BY d.Name HAVING COUNT(e.EmployeeID) "List all departme…

My own answers, with test data: https://gist.github.com/Pluies/5663135 Despite thinking I knew SQL reasonably well, I wouldn't have fared very well at all in an interview setting. :/ Took more time and googling than expected.

didnt google but I had to create some example data to think about the solutions. So yes, i would not be able to do it in 5 min.

Re: Our SQL interview questions

#132

Post by [deleted] »

kenko wrote: post #128
_pmf_ wrote: post #108

Earlier quoted context omitted.

> Seriously, what would be a valid reason to sort employees based on which specific editor they are habitually using? It's not for filtering out really good candidates, it's for filtering out abysmally bad candidates. Show me the dumbest Vi user and the dumbest Eclipse user you can find and you might learn something.

And people who've never used vi are ipso facto abysmally bad?

[deleted]

Re: Our SQL interview questions

#133

Post by SkippyZA »

I have just been on the job market looking for a senior PHP position. There were so many companies that requested tests from me. Either in the form of online tests, or tasks which I had to complete and return. While I do understand the need for them (having had to hire other developers), some of the requests were quite outrageous.

1 particular company basically wanted an entire application to be developed in an evening, and I was giving strict instructions to focus on security and not allowed to use external libraries. After submitting this elaborate task, I was still criticized on using PDO (which is standard with PHP...).

IMHO, sometimes the lengths employees go through to find a developer are so ridiculous that they actually drive away people.

Re: Our SQL interview questions

#134

Post by mgkimsal »

jfb wrote: post #118
mgkimsal wrote: post #110

Earlier quoted context omitted.

I've had this and have answered something like: "Compared to most other devs I work with, 7 or sometimes 8. Compared to people who do SQL for a living, possibly a 4, or a 5 if I'm feeling cocky. It all depends on what the '10' really represents - the best of the best, or the best of the people I'd be working with." Well, something like that. That last bit - I've said it more tactfully in the past.

This is the only way to answer this question.

Thanks :)

Said wrongly, it implies that the company has crap people working at it, and that's generally not a way to get hired. But most companies know they're not getting the 'best of the best' when they hire - they're getting the best they can afford in their geographic area during a certain time frame.

Re: Our SQL interview questions

#135

Post by Bognar »

jebblue wrote: post #90
oneandoneis2 wrote: post #37

Earlier quoted context omitted.

You've heard of the FizzBuzz test, right?

I heard about it in the last year or so here on HN, otherwise I wouldn't have known what a FizzBuzz was. I've been coding for 20 years professionally and 30 for fun. I've never coded a Fibonacci either. I think colleges need to teach how to code a microcontroller to do something, build a multi-platform application, build a database application, set up a CI server, etc.

We use FizzBuzz as a very basic first filter in our hiring process. It saves us a lot of interview time considering some 60% of candidates fail (or give ridiculously over-complicated implementations). Resumes are nothing but an exercise in creative writing, it seems.

Re: Our SQL interview questions

#136

Post by ndr »

porker wrote: post #53
jbverschoor wrote: post #30

Earlier quoted context omitted.

I don't run a school. Anytime a web-developer does not know basic sql or other basic knowledge, I refuse to pay salary, and even deduct the 1$ per minute. That five minutes just cost you $10

Bet you have one happy bunch of motivated developers working for you... that's an 'interesting' management style.

Most likely no one.

Re: Our SQL interview questions

#137

Post by _pmf_ »

kenko wrote: post #128
_pmf_ wrote: post #108

Earlier quoted context omitted.

> Seriously, what would be a valid reason to sort employees based on which specific editor they are habitually using? It's not for filtering out really good candidates, it's for filtering out abysmally bad candidates. Show me the dumbest Vi user and the dumbest Eclipse user you can find and you might learn something.

And people who've never used vi are ipso facto abysmally bad?

> And people who've never used vi are ipso facto abysmally bad?

A few false negatives might be acceptable.

Re: Our SQL interview questions

#138

Post by mgkimsal »

edw519 wrote: post #33

I took a similar test, on-line while being watched. 4 sets of 10 multiple choice questions: SQL, unix commands, vi, & HTML. Make your 10 choices, click submit, get your score. It was kinda silly, but what the heck... It was ridiculously easy and I got all 40 right without much thinking, as many people here would also, I imagine. Then I asked, "Why bother with this after reading my resume?" They answered, "We have to…

Took a similar test at a recruiting company in ... 2006 (IIRC). Mostly on PHP. And the test was wrong. IIRC, I got 24 out of 25. They were ecstatic - "wow, no one in this office ever got such a high score - you were almost perfect"

"I was," I said. "One of those questions is wrong".

"Oh, no, it couldn't be - we have a team of experts who create these to the highest standards, blah blah blah.".

I asked again to go back, take a picture (crappy camera phone) and reviewed it again when I got home. It was wrong. Something to do with how references behaved in PHP5, and the exam's answer was right for PHP4, but the test was for PHP5.

Anyway, it was a bit depressing, and I don't want to have to go through those sorts of tests again if I don't have to.

Re: Our SQL interview questions

#139

Post by T-hawk »

edw519 wrote: post #33

I took a similar test, on-line while being watched. 4 sets of 10 multiple choice questions: SQL, unix commands, vi, & HTML. Make your 10 choices, click submit, get your score. It was kinda silly, but what the heck... It was ridiculously easy and I got all 40 right without much thinking, as many people here would also, I imagine. Then I asked, "Why bother with this after reading my resume?" They answered, "We have to…

It's the state of the bottom of our industry. Those 52 programmers aren't a representative set of the general population. Those 52 programmers are the ones that can't catch on for any jobs so they keep applying over and over. It's a sampling bias.

And by the way, this happens for most industries, not just technology. McDonald's has the same problem. Their majority of applicants fail at tasks like having the literacy to fill out an application form or getting out of bed and showing up to work. This doesn't mean the majority of the population is that deficient, just the majority of deadweight floating around the would-be job pool.

More generally stated, the worse an applicant is for his desired job, the more times his incompetence will attend interviews to be seen. Quality performers in any business get hired quickly and don't stay in the interviewing pool. So equivalently, any interview pool will consist mostly of bad candidates.

We need a name for this effect so that we can just quote it whenever this topic comes up, like Dunning-Kruger. Anyone got a good suggestion? Joel Spolsky was the first to set it out well and become widely read[1] , but Spolsky's Law is already used for the Law of Leaky Abstractions.

[1] http://www.joelonsoftware.com/items/2005/01/27.html

Re: Our SQL interview questions

#140

Post by Tyrannosaurs »

jcampbell1 wrote: post #121
Tyrannosaurs wrote: post #14

Seems to me to be a solid test, though I might include a small amount of sample data to nudge them in the direction of some of the potential issues (empty departments and so on) - maybe I'm just kind like that. ;-) In interviews I've always been amazed how few people who claim to know SQL can use GROUP BY, HAVING and aggregate functions (or depending on the question self joins or sub queries that will allow them to a…

Removing duplicates is dependent on the underlying database because the behavior of deleting while selecting varies. I know MySQL doesn't allow it in most cases, so you need a temporary table. Identifying them is a fine question.

I give a basic single table schema with sample data so they have all the information they need to work with.
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