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What is the difference between UNION and UNION ALL?
...want the duplicates (especially when developing reports).
UNION Example:
SELECT 'foo' AS bar UNION SELECT 'foo' AS bar
Result:
+-----+
| bar |
+-----+
| foo |
+-----+
1 row in set (0.00 sec)
UNION ALL example:
SELECT 'foo' AS bar UNION ALL SELECT 'foo' AS bar
Result:
+-----+
| bar |
+---...
Which version of PostgreSQL am I running?
...
Run this query from PostgreSQL:
SELECT version();
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Is it possible to select the last n items with nth-child?
Using a standard list, I'm trying to select the last 2 list items. I've various permutations of An+B but nothing seems to select the last 2:
...
SQLAlchemy: print the actual query
...s:
print(str(statement))
This applies both to an ORM Query as well as any select() or other statement.
Note: the following detailed answer is being maintained on the sqlalchemy documentation.
To get the statement as compiled to a specific dialect or engine, if the statement itself is not already bo...
How to allow only one radio button to be checked?
... set "groups" of radio buttons, only one radio button in each group can be selected at one time and selecting other will clear the previous selection. :)
– Shadow Wizard is Ear For You
Mar 24 '11 at 13:02
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Displaying the Indian currency symbol on a website
...e and pastes it somewhere else, he will see Rs and not some other or blank character.
You can now also use the new Rupee unicode symbol — U+20B9 INDIAN RUPEE SIGN. It can be used in this manner:
<span class="WebRupee">&#x20B9;</span> 500
Just include the following script and it...
SQL UPDATE SET one column to be equal to a value in a related table referenced by a different column
...result set to update is before running the update (same query, just with a select):
select *
from QuestionTrackings q
inner join QuestionAnswers a
on q.AnswerID = a.AnswerID
where q.QuestionID is null -- and other conditions you might want
Particularly whether each answer id has definitely only 1...
How is the “greater than” or “>” character used in CSS?
I have seen this character a number of times in CSS files but I have no idea how its used. Can anyone explain it to me and show how they are useful in making a page style easier?
...
The Ruby %r{ } expression
...y, for legibility.
Edit:
Note that you can use almost any non-alphabetic character pair instead of '{}'.
These variants work just as well:
%r!/home/user!
%r'/home/user'
%r(/home/user)
Edit 2:
Note that the %r{}x variant ignores whitespace, making complex regexps more readable. Example from Git...
What columns generally make good indexes?
...earching the results speedily from tables. So it is most important step to select which columns to be indexed. There are two major places where we can consider indexing: columns referenced in the WHERE clause and columns used in JOIN clauses. In short, such columns should be indexed against which yo...