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Test if a variable is set in bash when using “set -o nounset”
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Nope, -, +, :+, and :- are all supported. The former detect whether the variable is set, and the latter detect whether it is set or empty. From man bash: "Omitting the colon results in a test only for a parameter that is unset."
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How to validate IP address in Python? [duplicate]
...ings like "4" and "192.168" and silently pads the rest with zeros. Technically valid, I'm sure, but not quite what I expected.
– krupan
Nov 25 '08 at 23:58
6
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Is it possible to roll back CREATE TABLE and ALTER TABLE statements in major SQL databases?
...cle Database 11g Release 2 and above - by default, no, but an alternative called edition-based redefinition exists
Older versions of Oracle - no; DDL causes an implicit commit
SQL Server - yes
Sybase Adaptive Server - yes
DB2 - yes
Informix - yes
Firebird (Interbase) - yes
SQLite also appears to h...
Bash script to cd to directory with spaces in pathname
I'm using Bash on macOS X and I'd like to create a simple executable script file that would change to another directory when it's run. However, the path to that directory has spaces in it. How the heck do you do this? This is what I have...
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Select first row in each GROUP BY group?
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On Oracle 9.2+ (not 8i+ as originally stated), SQL Server 2005+, PostgreSQL 8.4+, DB2, Firebird 3.0+, Teradata, Sybase, Vertica:
WITH summary AS (
SELECT p.id,
p.customer,
p.total,
ROW_NUMBER() OVER(PARTITION BY p.cus...
Removing duplicate values from a PowerShell array
...ay that only had a count of 1. It was not clear if this is what the OP actually wanted however I was unable to find an example of this solution online so here it is.
$array=@'
Bananna
Apple
Carrot
Pear
Apricot
Pear
Bananna
'@ -split '\r\n'
($array | Group-Object -NoElement | ?{$_.count -eq 1}).Nam...
How do I pass command-line arguments to a WinForms application?
...= "/lol"; args[3] = "nisp"; What could be easier?
– Callum Rogers
Jul 24 '09 at 19:22
cant believe i saw that 'string[...
How do I print to the debug output window in a Win32 app?
...you can use the L prefix:
OutputDebugStringW(L"My output string.");
Normally you will use the macro version together with the _T macro like this:
OutputDebugString(_T("My output string."));
If you project is configured to build for UNICODE it will expand into:
OutputDebugStringW(L"My output s...
What do Clustered and Non clustered index actually mean?
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With a clustered index the rows are stored physically on the disk in the same order as the index. Therefore, there can be only one clustered index.
With a non clustered index there is a second list that has pointers to the physical rows. You can have many non clustered ind...
How do I append text to a file?
...ther source.
Or else entered at the keyboard, doesn't matter.
^D
Essentially, you can dump any text you want into the file. CTRL-D sends an end-of-file signal, which terminates input and returns you to the shell.
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