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List tables in a PostgreSQL schema
...nslated to the regular-expression notation .*, ? which is translated to ., and $ which is matched literally. You can emulate these pattern characters at need by writing ? for ., (R+|) for R*, or (R|) for R?. $ is not needed as a regular-expression character since the pattern must match the whole nam...
Regex for splitting a string using space when not surrounded by single or double quotes
I'm new to regular expressions and would appreciate your help. I'm trying to put together an expression that will split the example string using all spaces that are not surrounded by single or double quotes. My last attempt looks like this: (?!") and isn't quite working. It's splitting on the spa...
OO Design in Rails: Where to put stuff
I'm really enjoying Rails (even though I'm generally RESTless), and I enjoy Ruby being very OO. Still, the tendency to make huge ActiveRecord subclasses and huge controllers is quite natural (even if you do use a controller per resource). If you were to create deeper object worlds, where would you p...
What is the Oracle equivalent of SQL Server's IsNull() function?
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coalesce is supported in both Oracle and SQL Server and serves essentially the same function as nvl and isnull. (There are some important differences, coalesce can take an arbitrary number of arguments, and returns the first non-null one. The return type for isn...
How to read from a file or STDIN in Bash?
...e following Perl script ( my.pl ) can read from either the file on the command line args or from STDIN:
15 Answers
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How to sort the result from string_agg()
...he question was about string_agg. Postgres was incidental to his question and he mentioned it last. The question is useful to others as well.
– nomen
Mar 5 at 17:42
1
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Wireshark localhost traffic capture [closed]
...ssible - read below. You can use the local address of your machine instead and then you'll be able to capture stuff. See CaptureSetup/Loopback.
Summary: you can capture on the
loopback interface on Linux, on
various BSDs including Mac OS X, and
on Digital/Tru64 UNIX, and you might
be abl...
Visual Studio Immediate window: how to see more than the first 100 items
... this is way late. However, If you add your object to the watch window. Expand the properties, where all are displayed. Then Ctrl-A and Copy. You can then paste in excel to get an organized list of properties and their values.
...
Convert data.frame column format from character to factor
... of the variables (all numeric)
#one approach it to index with the $ sign and the as.factor function
mtcars$am <- as.factor(mtcars$am)
#another approach
mtcars[, 'cyl'] <- as.factor(mtcars[, 'cyl'])
str(mtcars) # now look at the classes
This also works for character, dates, integers and ot...
mongodb group values by multiple fields
...takes an "pipeline" expression as an argument instead of the "localFields" and "foreignFields" options. This then allows a "self-join" with another pipeline expression, in which we can apply $limit in order to return the "top-n" results.
db.books.aggregate([
{ "$group": {
"_id": "$addr",
"...