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CROSS JOIN vs INNER JOIN in SQL
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2. CROSS JOIN
Cross join selects the all the rows from the first table and all the rows from second table and shows as Cartesian product ie, with all possibilities
Consider we need to find all the teachers in the school and students irrespective of class teacher...
Reset the database (purge all), then seed a database
... the whole shebang just to reload your data, you could use MyModel.destroy_all (or delete_all) in the seed.db file to clean out a table before your MyModel.create!(...) statements load the data. Then, you can redo the db:seed operation over and over. (Obviously, this only affects the tables you've...
How to view corresponding SQL query of the Django ORM's queryset?
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You also can use python logging to log all queries generated by Django. Just add this to your settings file.
LOGGING = {
'disable_existing_loggers': False,
'version': 1,
'handlers': {
'console': {
# logging handler that outputs log...
Why does Double.NaN==Double.NaN return false?
...enormalized value or a signed zero, and an operation that has no mathematically definite result produces NaN. All numeric operations with NaN as an operand produce NaN as a result. As has already been described, NaN is unordered, so a numeric comparison operation involving one or two NaNs returns fa...
How do I 'svn add' all unversioned files to SVN?
I'm looking for a good way to automatically 'svn add' all unversioned files in a working copy to my SVN repository.
19 An...
Get all files that have been modified in git branch
... between your current branch and <some-other-branch>. So it's essentially the same command, but note that you can use this to find the files that are different between any two branches, even if they're not remotely related. Whether that comparison is useful or not depends on the topology of yo...
How can I use Autolayout to set constraints on my UIScrollview?
... Apple describes in the Technical Note.
I also had a lot of trouble originally getting Auto Layout to work with UIScrollView. The key to getting it to work is making sure that all of the items in the scroll view, taken together, have constraints that eventually link to all sides of the scroll view ...
Is there a way to “autosign” commits in Git with a GPG key?
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Note: if you don't want to add -S all the time to make sure your commits are signed, there is a proposal (branch 'pu' for now, December 2013, so no guarantee it will make it to a git release) to add a config which will take care of that option for you.
Update...
How to apply specific CSS rules to Chrome only?
...get the Google Chrome,using media queries or CSS hacks,but Javascript is really more effective.
Here is the piece of Javascript code that will target Google Chrome 14 and later,
var isChrome = !!window.chrome && !!window.chrome.webstore;
and below is a list of Available Browser hacks,f...
How to get all files under a specific directory in MATLAB?
I need to get all those files under D:\dic and loop over them to further process individually.
8 Answers
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