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R: Comment out block of code [duplicate]
...tors use something like command or control and single quote to comment out selected lines of code. In RStudio it's Command or Control+/. Check in your editor.
It's still commenting line by line, but they also uncomment selected lines as well. For the Mac RGUI it's command-option ' (I'm imagining...
How to pull a random record using Django's ORM?
...on't know about other databases).
order_by('?')[:N] will be translated to SELECT ... FROM ... WHERE ... ORDER BY RAND() LIMIT N query.
It means that for every row in table the RAND() function will be executed, then the whole table will be sorted according to value of this function and then first N...
What is a “batch”, and why is GO used?
...add a column to a table, then it should be in its own batch.
If you try to SELECT the new column in the same batch it fails because at parse/compile time the column does not exist.
GO is used by the SQL tools to work this out from one script: it is not a SQL keyword and is not recognised by the eng...
Update or Insert (multiple rows and columns) from subquery in PostgreSQL
...table.col1 = 123;
For the INSERT
Use:
INSERT INTO table1 (col1, col2)
SELECT col1, col2
FROM othertable
You don't need the VALUES syntax if you are using a SELECT to populate the INSERT values.
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Eclipse: Enable autocomplete / content assist
...efault in Eclipse you only have to press Ctrl-space for autocomplete. Then select the desired method and wait 500ms for the javadoc info to pop up.
If this doesn't work go to the Eclipse Windows menu -> Preferences -> Java -> Editor -> Content assist and check your settings here
...
How to download source in ZIP format from GitHub?
... under the Code tab:
If you don't see the button:
Make sure you've selected <> Code tab from right side navigation menu, or
Repo may not have a zip prepared. Add /archive/master.zip to the end of the repository URL and to generate a zipfile of the master branch:
http://github.com/use...
SQL-Server: The backup set holds a backup of a database other than the existing
...go for the restore option
Under Options on the left pane don't forget to select
Overwrite the existing database
Preserve the replication settings
That's it
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Table Naming Dilemma: Singular vs. Plural Names [closed]
...
Customer
Customer.CustomerID
CustomerAddress
public Class Customer {...}
SELECT FROM Customer WHERE CustomerID = 100
Once you know you are dealing with "Customer", you can be sure you will use the same word for all of your database interaction needs.
Reason 5. (Globalization). The world is gettin...
How to compile a 64-bit application using Visual C++ 2010 Express?
... dialog box there will be a "Configuration" drop-down menu. Make sure that selects "All Configurations." There will also be a "Platform" drop-down that will read "Win32." Finally on the right there is a "Configuration Manager" button - press it. In the dialog that comes up, find your project, hit th...
How random is JavaScript's Math.random?
...
90 have 2 digits
900 have 3 digits
1 has 4 digits
and so on.
So if you select some at random, then that vast majority of selected numbers will have the same number of digits, because the vast majority of possible values have the same number of digits.
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