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How to add column if not exists on PostgreSQL?
...
Here's a short-and-sweet version using the "DO" statement:
DO $$
BEGIN
BEGIN
ALTER TABLE <table_name> ADD COLUMN <column_name> <column_type>;
EXCEPTION
WHEN duplicate_column THE...
How to properly import a selfsigned certificate into Java keystore that is available to all Java app
...Windows the easiest way is to use the program portecle.
Download and install portecle.
First make 100% sure you know which JRE or JDK is being used to run your program. On a 64 bit Windows 7 there could be quite a few JREs. Process Explorer can help you with this or you can use: System.out.println...
How To Check If A Key in **kwargs Exists?
...efix variable. If it is given, then its value is being used.
This is generally a compact and readable recipe for writing wrappers for any kind of function: Always just pass-through arguments you don't understand, and don't even know if they exist. If you always pass through *args and **kwargs you m...
What is INSTALL_PARSE_FAILED_NO_CERTIFICATES error?
I was trying to change my default/main/startup (whatever you call it) activity by editing the androidmanifest.xml file. All i did was change the android:name property. however, this completely broke the entire app. when I try to install it fails and reads.
...
How to have git log show filenames like svn log -v
...ncouraged to use
git-log[1] instead. The
whatchanged command is essentially the same as
git-log[1] but defaults to show
the raw format diff output and to skip merges.
The command is kept primarily for historical reasons; fingers of many
people who learned Git long before git log was i...
Convert string to binary in python
...rent version 3.7.4): (1) bytearray expects an encoding (not just a string) and (2) map(bin, ...) will return the map object. For the first point, I use for instance bob.encoding('ascii')` as suggested by @Tao. For the second, point, using the join method, as in the other examples of @Kasramvd will ...
How do I create delegates in Objective-C?
...ign it as the web view's delegate:
MyClass *instanceOfMyClass = [[MyClass alloc] init];
myWebView.delegate = instanceOfMyClass;
On the UIWebView side, it probably has code similar to this to see if the delegate responds to the webViewDidStartLoad: message using respondsToSelector: and send it if ...
What should main() return in C and C++?
...d termination) according to the C++ standard. For C, re-entering main() is allowed, but should be avoided.
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Which way is best for creating an object in JavaScript? Is `var` necessary before an object property
...your example, Person (you should start the name with a capital letter) is called the constructor function. This is similar to classes in other OO languages.
Use way 2 if you only need one object of a kind (like a singleton). If you want this object to inherit from another one, then you have to use a...
How to concatenate strings in django templates?
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I was totally confused by this answer as it uses the include tag instead of the extend tag, but apparently it just works. Though I would recommend Ahsan's own answer as it also workes and is (in my opinion) semantically more correct a...