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quick random row selection in Postgres
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You might want to experiment with OFFSET, as in
SELECT myid FROM mytable OFFSET floor(random()*N) LIMIT 1;
The N is the number of rows in mytable. You may need to first do a SELECT COUNT(*) to figure out the value of N.
Update (by Antony Hatchkins)
You must use floor he...
Get the week start date and week end date from week number
...y other weird value to test it */
DECLARE @d DATETIME
SET @d = GETDATE()
SELECT
@d ThatDate,
DATEADD(dd, 0 - (@@DATEFIRST + 5 + DATEPART(dw, @d)) % 7, @d) Monday,
DATEADD(dd, 6 - (@@DATEFIRST + 5 + DATEPART(dw, @d)) % 7, @d) Sunday
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In Ruby, is there an Array method that combines 'select' and 'map'?
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I usually use map and compact together along with my selection criteria as a postfix if. compact gets rid of the nils.
jruby-1.5.0 > [1,1,1,2,3,4].map{|n| n*3 if n==1}
=> [3, 3, 3, nil, nil, nil]
jruby-1.5.0 > [1,1,1,2,3,4].map{|n| n*3 if n==1}.compact
=> ...
Insertion Sort vs. Selection Sort
I am trying to understand the differences between Insertion Sort and Selection Sort.
20 Answers
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Why is SELECT * considered harmful?
Why is SELECT * bad practice? Wouldn't it mean less code to change if you added a new column you wanted?
15 Answers
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Changing selection in a select with the Chosen plugin
I'm trying to change the currently selected option in a select with the Chosen plugin.
4 Answers
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You can't specify target table for update in FROM clause
...llow you to write queries like this:
UPDATE myTable
SET myTable.A =
(
SELECT B
FROM myTable
INNER JOIN ...
)
That is, if you're doing an UPDATE/INSERT/DELETE on a table, you can't reference that table in an inner query (you can however reference a field from that outer table...)
Th...
How to make an Android Spinner with initial text “Select One”?
I want to use a Spinner that initially (when the user has not made a selection yet) displays the text "Select One". When the user clicks the spinner, the list of items is displayed and the user selects one of the options. After the user has made a selection, the selected item is displayed in the Spi...
Initializing select with AngularJS and ng-repeat
I'm trying to get select-box to start off with a pre-filled option using ng-repeat with AngularJS 1.1.5. Instead the select always starts out with nothing selected. It also has an empty option, which I don't want. I think that there is a side effect of nothing being selected.
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Is it possible to style a select box? [closed]
I've got an HTML select box that I need to style. I'd prefer to use just CSS but if I have to I'll use jQuery to fill in the gaps.
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