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Update multiple rows in same query using PostgreSQL
... one column, it's much more generalizable:
update test as t set
column_a = c.column_a
from (values
('123', 1),
('345', 2)
) as c(column_b, column_a)
where c.column_b = t.column_b;
You can add as many columns as you like:
update test as t set
column_a = c.column_a,
column_c...
What is the _snowman param in Ruby on Rails 3 forms for?
...n Ruby on Rails 3 (currently using Beta 4), I see that when using the form_tag or form_for helpers there is a hidden field named _snowman with the value of ☃ ( Unicode \x9731) showing up.
...
Can I find events bound on an element with jQuery?
...
In modern versions of jQuery, you would use the $._data method to find any events attached by jQuery to the element in question. Note, this is an internal-use only method:
// Bind up a couple of event handlers
$("#foo").on({
click: function(){ alert("Hello") },
mous...
How to .gitignore files recursively
... the repo root (parent directory of /Webapp).
– lucid_dreamer
May 6 '18 at 22:33
1
...
Numpy - add row to array
...m adding on matrix A
1 2 3
4 5 6
with a row
7 8 9
same usage in np.r_
A= [[1, 2, 3], [4, 5, 6]]
np.append(A, [[7, 8, 9]], axis=0)
>> array([[1, 2, 3],
[4, 5, 6],
[7, 8, 9]])
#or
np.r_[A,[[7,8,9]]]
Just to someone's intersted, if you would like to add...
ValueError: The truth value of an array with more than one element is ambiguous. Use a.any() or a.al
...rrays causes the two arrays to be evaluated in boolean context (by
calling __bool__ in Python3 or __nonzero__ in Python2).
Your original code
mask = ((r["dt"] >= startdate) & (r["dt"] <= enddate))
selected = r[mask]
looks correct. However, if you do want and, then instead of a and b u...
Play a Sound with Python [duplicate]
...t's built in
import winsound
winsound.PlaySound('sound.wav', winsound.SND_FILENAME)
You should be able to use ossaudiodev for linux:
from wave import open as waveOpen
from ossaudiodev import open as ossOpen
s = waveOpen('tada.wav','rb')
(nc,sw,fr,nf,comptype, compname) = s.getparams( )
dsp = os...
Skip certain tables with mysqldump
...!/bin/bash
PASSWORD=XXXXXX
HOST=XXXXXX
USER=XXXXXX
DATABASE=databasename
DB_FILE=dump.sql
EXCLUDED_TABLES=(
table1
table2
table3
table4
tableN
)
IGNORED_TABLES_STRING=''
for TABLE in "${EXCLUDED_TABLES[@]}"
do :
IGNORED_TABLES_STRING+=" --ignore-table=${DATABASE}.${TABLE}"
done
echo "Dump st...
What are the differences between numpy arrays and matrices? Which one should I use?
...
Or just np.linalg.matrix_power(mat, n)
– Eric
Feb 28 '17 at 11:16
I...
In MySQL, can I copy one row to insert into the same table?
...rd Challis's technique with a few changes:
CREATE TEMPORARY TABLE tmptable_1 SELECT * FROM table WHERE primarykey = 1;
UPDATE tmptable_1 SET primarykey = NULL;
INSERT INTO table SELECT * FROM tmptable_1;
DROP TEMPORARY TABLE IF EXISTS tmptable_1;
As a temp table, there should never be more than o...