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Swapping column values in MySQL
...test s1, swap_test s2 SET s1.x=s1.y, s1.y=s2.x WHERE s1.id=s2.id;
Essentially, the 1st table is the one getting updated and the 2nd one is used to pull the old data from.
Note that this approach requires a primary key to be present.
This is my test schema:
CREATE TABLE `swap_test` (
`id` int(1...
What is the exact problem with multiple inheritance?
I can see people asking all the time whether multiple inheritance should be included into the next version of C# or Java. C++ folks, who are fortunate enough to have this ability, say that this is like giving someone a rope to eventually hang themselves.
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The most accurate way to check JS object's type?
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@jamietre because "foo" instanceof String breaks
– Raynos
Oct 25 '11 at 18:58
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How to create id with AUTO_INCREMENT on Oracle?
...NCREMENT by 1),
c2 VARCHAR2(10)
);
Alternatively, Oracle 12 also allows to use a sequence as a default value:
CREATE SEQUENCE dept_seq START WITH 1;
CREATE TABLE departments (
ID NUMBER(10) DEFAULT dept_seq.nextval NOT NULL,
DESCRIPTION VARCHAR2(50) NOT NULL);
ALTER T...
General suggestions for debugging in R
...orite debugging routine:
When an error occurs, the first thing that I usually do is look at the stack trace by calling traceback(): that shows you where the error occurred, which is especially useful if you have several nested functions.
Next I will set options(error=recover); this immediately sw...
Why do assignment statements return a value?
This is allowed:
14 Answers
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sed edit file in place
... out if it is possible to edit a file in a single sed command without manually streaming the edited content into a new file and then renaming the new file to the original file name. I tried the -i option but my Solaris system said that -i is an illegal option. Is there a different way?
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What does “var FOO = FOO || {}” (assign a variable or an empty object to that variable) mean in Java
...tional arguments and initialize them to defaults if not provided: function foo(arg1, optarg1, optarg2) { optarg1 = optarg1 || 'default value 1'; optarg2 = optart2 || 'defalt value 2';}
– crazy2be
Jun 22 '11 at 19:24
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Understanding events and event handlers in C#
I understand the purpose of events, especially within the context of creating user interfaces. I think this is the prototype for creating an event:
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How do I copy an entire directory of files into an existing directory using Python?
... containing one or more files). Make sure there is not a directory named foo .
14 Answers
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