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What's wrong with nullable columns in composite primary keys?
...ow in a table: when a table has a primary key, you have a guranteed way to select any row from it.
A unique constraint does not necessarily identify every row; it just specifies that if a row has values in its columns, then they must be unique. This is not sufficient to uniquely identify every row...
Quickly reading very large tables as dataframes
...
# sqldf as on SO
f <- file("test.csv")
system.time(SQLf <- sqldf("select * from f", dbname = tempfile(), file.format = list(header = T, row.names = F)))
## user system elapsed
## 10.21 0.47 10.73
ff / ffdf
require(ff)
system.time(FFDF <- read.csv.ffdf(file="test.csv",nro...
How can I remove the extension of a filename in a shell script?
...also known as separator) for cutting the string into segments and by -f we select which segment we want to have in output
Then the $() command substitution will get the output and return its value
The returned value will be assigned to the variable named name
Note that this gives the portion of th...
Incorrect syntax near ')' calling stored procedure with GETDATE
...N
set @DateVar=ISNULL(@DateVar,GETDATE())
--the SP stuff here
SELECT @DateVar
END
GO
And then try:
EXEC DisplayDate '2013-02-01 00:00:00.000'
EXEC DisplayDate
Remark: Here I supposed that NULL value is not in use for this parameter. If it is not your case - you can use another unus...
Objective-C Split()?
...hat are AGES old and have established answers... Not to mention yours just selects the first element which makes no sense.
– Christian Stewart
Dec 22 '14 at 5:22
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How do you comment out code in PowerShell?
...hin PowerShell ISE you can hit Ctrl+J to open the Start Snipping menu and select Comment block:
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Admob Error in Eclipse for android:configChanges
...get.
target=android-13
Step 2:
In Eclipse
Project > Clean... > (select your project) > Clean projects selected below > OK
For a complete explanation with real example use this tutorial http://www.monkeycoder.co.nz/Community/posts.php?topic=1121
Cheers !
...
Convert number to month name in PHP
...mes from the beginning of the year to the end e.g. to populate a drop-down select, I would just use the following;
for ($i = 0; $i < 12; ++$i) {
$months[$m] = $m = date("F", strtotime("January +$i months"));
}
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How to set input type date's default value to today?
...ing mobile. On Android 4.0.3 (at least) I've had issues where the new date selected via the popup date control is appended to todays date, rather than replaces it. E.g. you can end up with 2013-03-252013-03-27 rather than 2013-03-25, and there's no way for the user to change it.
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SQL: How to get the count of each distinct value in a column?
...
SELECT
category,
COUNT(*) AS `num`
FROM
posts
GROUP BY
category
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