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I could nail those with the Django ORM, but I'd struggle to write syntactically correct SQL, not having done it in a while. But it says that your test machine has MS-SQL; with the machine in front of me, I could probably puzzle it out the join quirks with a couple minutes of trial and error.
How would you solve the first one using Django ORM?
from .models import Employee
from django.db.models import F
print Employee.objects.filter(
salary__gt=F('boss__salary')
)Anyway, some of the other questions were pretty silly like "Which of the following is a DDL command?", and many were SELECT statements with a syntax error that you had to pick out, and probably the one question that made sense was about the difference between WHERE and HAVING.
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True story, but such questions are just senseless. If someone knows about set-theory and the ideas behind query-languages, knowing SQL isn't a deal breaker, it's just a nice to have.
Folk generally don't study relational algebra, on its own, for fun.
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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 $10
Ignoring the fact that 1$/minute * 5minutes = 5$ -- I wonder which _knowledgeable_ person is willing to work with someone who thinks like you do...
This person did not qualify to be _knowledgeable_, as he refused to do this test ;)
"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…
Curious question: why do you always use table aliases? To keep your query shorter? When I don't need an alias I just use the full table name for readability: SELECT Department.Name, COUNT(Employees.EmployeeID) FROM Department JOIN Employees ON Employees.DepartmentID = Department.DepartmentID GROUP BY Department.Name HAVING COUNT(Employees.EmployeeID)
Ask people about difference between LEFT JOIN and RIGHT JOIN, or using the schema from the article, to select all attributes of employees with the highest salary in their department in pure SQL and you will see how much or how little people know, in fact many webdevs don't even understand JOINs at all!
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I came to Oracle after it adopted the ANSI syntax, so that's what I use. So my experience is the opposite of yours -- when I see the (+) I need to look up the syntax to remember if it's left or right outer.
And then I ask, hey, where's my BOOLEAN? And then I drink.
And the lack of a serial/autoincrement/identity type.
So. Many. Effing. Triggers.
And 32-character identifiers.
sigh
SELECT Departments.name, SUM(COALESCE(salary,0))
FROM Departments
LEFT JOIN employees USING departmentID
GROUP BY 1
Which book would you recommend for learning this stuff? I'm not very interested in 800-p. gorillas; there surely must be something short, not too theoretical, and to the point.
I'm not a SQL Developer, but anytime I get questions for which Google has answers to be found in 5 minutes or less, I'm quite hesitant to work there. I respect interviews that go along the lines of: "What would you do if..." after giving a detailed description of their environment. But then again I'm a tools/OSes admin, so maybe it makes more sense for my job description. But anytime guys are too focused on third opt…
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