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Is there any difference between GROUP BY and DISTINCT
...s. Use GROUPY BY if you want to apply aggregate operators (MAX, SUM, GROUP_CONCAT, ..., or a HAVING clause).
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How to find current transaction level?
... SET
ansi_padding SET
ansi_nulls SET
concat_null_yields_null SET
isolation level read committed
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RE error: illegal byte sequence on Mac OS X
...'s/./@/' <<<$'\xfc' fails, because byte 0xfc is not a valid UTF-8 char.
Note that, by contrast, GNU sed (Linux, but also installable on macOS) simply passes the invalid byte through, without reporting an error.
Using the formerly accepted answer is an option if you don't mind losing suppor...
What is the best way to concatenate two vectors?
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Depends on whether you really need to physically concatenate the two vectors or you want to give the appearance of concatenation of the sake of iteration. The boost::join function
http://www.boost.org/doc/libs/1_43_0/libs/range/doc/html/range/reference/utilities/join.html
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Calling Objective-C method from C++ member function?
...d );
int doSomethingWith( void * aParameter );
void logMyMessage( char * aCStr );
private:
void * self;
};
#endif
Notice the wrapper methods no longer require the void pointer to an instance of MyClass; it is now a private member of MyClassImpl. The init method is used to instantia...
Count the number of occurrences of a character in a string in Javascript
I need to count the number of occurrences of a character in a string.
33 Answers
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Lua简明教程 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...应表达式 a ^ b
__unm(a) 对应表达式 -a
__concat(a, b) 对应表达式 a .. b
__len(a) 对应表达式 #a
__eq(a, b) 对应表达式 a == b
__lt(a, b) 对应表达式 a < b
__le(a, b...
Remove all special characters from a string [duplicate]
...t titles that could contain anything and have them stripped of all special characters so they only have letters and numbers and of course I would like to replace spaces with hyphens.
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Stop Excel from automatically converting certain text values to dates
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In my MySQL query (for CSV output through PHP), I used CONCAT('\t', column_name). Also did the trick. Thanks!
– Just Plain High
Jun 24 '16 at 14:39
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What's the point of malloc(0)?
...que pointer that can be passed to free"), but if you're treating this as a char*, that may give you an invalid, non-terminated char. It could be dangerous to rely on this in cross-platform situations.
– Reed Copsey
Jan 7 '10 at 17:51
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