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Can a foreign key be NULL and/or duplicate?
...at field must exist first in a different table (the parent table). That is all an FK is by definition. Null by definition is not a value. Null means that we do not yet know what the value is.
Let me give you a real life example. Suppose you have a database that stores sales proposals. Suppose furth...
PG undefinedtable error relation users does not exist
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At first, you shall detach all connections out of database. By default you use the development environment. Then try to reset database with the following:
rake db:reset
The rake db:reset task will drop the database and set it up again....
Start two instances of IntelliJ IDE
...edition).
When I have one instance started and I try to start another one, all that happens is that my started instance gets focus.
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How to open a second activity on click of button in android app
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but where? I get errors all over the place If i try place this withing the .java in eclipse
– Henry Aspden
Nov 2 '12 at 12:08
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The first day of the current month in php using date_modify as DateTime object
... This is IMO by far the simplest and most readable way to solve this, if all you need is a string representation of the date.
– Markus Amalthea Magnuson
Aug 17 '12 at 11:23
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How to read a CSV file into a .NET Datatable
...ns values, so coming up with a regex that would split the line was kinda challenging. The OleDbProvider inferred the schema correctly.
– Galilyou
Jan 14 '12 at 10:41
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Using multiple property files (via PropertyPlaceholderConfigurer) in multiple projects/modules
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If you add all file in 1 tag, then don't event need ignore-unresolvable="true", otherwise need.
– Eric Wang
May 8 '15 at 10:43
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Ninject vs Unity for DI [closed]
...ation to derive from NinjectHttpApplication, spin up the Kernel in it and call RegisterAllControllersIn(Assembly.GetExecutingAssembly()) to have it take care of all controllers in the given assembly. Magic.
– Michael Stum♦
Dec 28 '09 at 13:48
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Why does TestInitialize get fired for every test in my Visual Studio unit tests?
...re that no tests are coupled.
If you want to run methods before and after ALL tests, decorate relevant methods with the ClassInitialize and ClassCleanup attributes.
Relevant information from the auto generated test-file in Visual Studio:
You can use the following additional attributes as you writ...
Can TCP and UDP sockets use the same port?
First of all, is there any problem with using both UDP and TCP on the same server?
2 Answers
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