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How to find gaps in sequential numbering in mysql?
... far faster than the accepted answer. The only thing that I'd add is that CONVERT( YourCol, UNSIGNED ) will give better results if YourCol isn't already an integer.
– Barton Chittenden
Feb 10 '17 at 23:36
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What is the best way to paginate results in SQL Server
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Getting the total number of results and paginating are two different operations. For the sake of this example, let's assume that the query you're dealing with is
SELECT * FROM Orders WHERE OrderDate >= '1980-01-01' ORDER BY OrderDate
In this case, you wou...
How to save all the variables in the current python session?
...s()[key]
except TypeError:
#
# __builtins__, my_shelf, and imported modules can not be shelved.
#
print('ERROR shelving: {0}'.format(key))
my_shelf.close()
To restore:
my_shelf = shelve.open(filename)
for key in my_shelf:
globals()[key]=my_shelf[key]
my_she...
第一个Hello,OS World操作系统 - 操作系统(内核) - 清泛网 - 专注C/C++及内核技术
...看本节例子最终运行效果：
编译运行环境：
nasm：Inter x86汇编编译工具，用户将我们的汇编代码编译为二进制。（下载地址）
Bochs：运行os的虚拟机工具，模拟加载我们生成的软盘映像，并运行os。（下载地址）
代码...
Avoiding SQL injection without parameters
...weird. The parser is capable of identifying constants in the text and can convert the SQL string to one the uses parameters artificially. It can then insert into the cache the text of this new parameterised query. Subsequent similar SQL may find its parameterised version matched in the cache. Ho...
How to find out which fonts are referenced and which are embedded in a PDF document
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You can extract font(s) from PDF using Online Font Converter
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Linq: GroupBy, Sum and Count
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I don't understand where the first "result with sample data" is coming from, but the problem in the console app is that you're using SelectMany to look at each item in each group.
I think you just want:
List<ResultLine> result = Lin...
Can I mix Swift with C++? Like the Objective-C .mm files
I just changed my .m files to .mm and use C++. Is there a way to do the same with Swift?
13 Answers
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Selecting multiple columns in a pandas dataframe
...n interface to NumPy's usual __getitem__ syntax. That said, you can easily convert a column-slicing problem into a row-slicing problem by just applying a transpose operation, df.T. Your example uses columns[1:3], which is a little misleading. The result of columns is a Series; be careful not to just...
When should I use C++ private inheritance?
...This is NOT a complete answer. Read other answers like here (conceptually) and here (both theoretic and practic) if you are interested in the question. This is just a fancy trick that can be achieved with private inheritance. While it is fancy it is not the answer to the question.
Besides the basic...