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Postgres: INSERT if does not exist already
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Postgres 9.5 (released since 2016-01-07) offers an "upsert" command, also known as an ON CONFLICT clause to INSERT:
INSERT ... ON CONFLICT DO NOTHING/UPDATE
It solves many of the subtle problems you can run into when using concurrent operation, which some other answers propose.
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Git blame — prior commits?
... Can you get a complete history, without having to re-enter the command several times with different hashes?
– Anders Zommarin
Feb 23 '11 at 22:59
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Django: Get list of model fields?
....AutoField: id>, <django.db.models.fields.DateField: created>...
and
Organisation._meta.get_fields()
(<ManyToOneRel: crm.activity>, <django.db.models.fields.AutoField: id>, <django.db.models.fields.DateField: created>...
2) From instance
from posts.model import BlogPost
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Download single files from GitHub
I guess most of you, developers, use any VCS , and I hope some of you use Git. Do you have any tip or trick how to get a download URL for a single file in a repository?
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How to tell which commit a tag points to in Git?
I have a bunch of unannotated tags in the repository and I want to work out which commit they point to. Is there a command that that will just list the tags and their commit SHAs? Checking out the tag and looking at the HEAD seems a bit too laborious to me.
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Environment variable to control java.io.tmpdir?
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Hmmm -- since this is handled by the JVM, I delved into the OpenJDK VM source code a little bit, thinking that maybe what's done by OpenJDK mimics what's done by Java 6 and prior. It isn't reassuring that there's a way to do this other than on Win...
Plot two histograms on single chart with matplotlib
I created a histogram plot using data from a file and no problem. Now I wanted to superpose data from another file in the same histogram, so I do something like this
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SQL Server Text type vs. varchar data type [closed]
I have variable length character data and want to store in SQL Server (2005) database. I want to learn some best practices about how to choose TEXT SQL type or choose VARCHAR SQL type, pros and cons in performance/footprint/function.
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Dilemma: when to use Fragments vs Activities:
...tivity can hold all duplicated elements to save you time in creating them, and you can simply replace parts of the box.
But don't forget that you always need a box container (Activity) or your parts will be dispersed. So one box with parts inside.
Take care not to misuse the box. Android UX exper...
Remove unnecessary svn:mergeinfo properties
...nk the idea is to just go to the dir that has all the messed up merge info and do it from there, so you don't have to revert the root directory. You don't want to mess with the mergeinfo of the root.
– JeremyWeir
Apr 26 '16 at 18:09
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