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How to add column if not exists on PostgreSQL?
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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 THEN RAISE NOTICE 'colu...
android on Text Change Listener
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You can add a check to only clear when the text in the field is not empty (i.e when the length is different than 0).
field1.addTextChangedListener(new TextWatcher() {
@Override
public void afterTextChanged(Editable s) {}
@Override
public void beforeTextC...
find vs find_by vs where
I am new to rails. What I see that there are a lot of ways to find a record:
12 Answers
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Difference between CPPFLAGS and CXXFLAGS in GNU Make
What's the difference between CPPFLAGS and CXXFLAGS in GNU Make?
4 Answers
4
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How to Turn Off Showing Whitespace Characters in Visual Studio IDE
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CTRL+R, CTRL+W : Toggle showing whitespace
or under the Edit Menu:
Edit -> Advanced -> View White Space
[BTW, it also appears you are using Tabs. It's common practice to have the IDE turn Tabs into spaces (often 4), via Options.]
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How to solve “Fatal error: Class 'MySQLi' not found”?
I am doing a tutorial and am getting this error:
22 Answers
22
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How to show line number when executing bash script
...error occurs. However, it's still rather difficult for me to locate which line did the execution stop in order to locate the problem.
Is there a method which can output the line number of the script before each line is executed?
Or output the line number before the command exhibition generated by s...
When correctly use Task.Run and when just async-await
I would like to ask you on your opinion about the correct architecture when to use Task.Run . I am experiencing laggy UI in our WPF .NET 4.5
application (with Caliburn Micro framework).
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“unrecognized import path” with go get
I'm trying to install a web.go , but running go get github.com/hoisie/web returns
9 Answers
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Using querySelectorAll to retrieve direct children
...estion. At the time it was asked, a universally-implemented way to do "combinator rooted queries" (as John Resig called them) did not exist.
Now the :scope pseudo-class has been introduced. It is not supported on [pre-Chrominum] versions of Edge or IE, but has been supported by Safari for a few yea...