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Linux MySql编译安装 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...d mysql
useradd -g mysql mysql
#开始编译安装
cmake -DCMAKE_INSTALL_PREFIX=/usr/local/mysql \
-DMYSQL_UNIX_ADDR=/tmp/mysql.sock \
-DDEFAULT_CHARSET=utf8 \
-DDEFAULT_COLLATION=utf8_general_ci \
-DWITH_EXTRA_CHARSETS=all \
-DWITH_MYISAM_STORAGE_ENGINE=1 \
-DWITH_INNOBASE_STORAGE_ENGIN...
count(*) vs count(column-name) - which is more correct? [duplicate]
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COUNT(*) counts all rows
COUNT(column) counts non-NULLs only
COUNT(1) is the same as COUNT(*) because 1 is a non-null expressions
Your use of COUNT(*) or COUNT(column) should be based on the desired output only.
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Why do you use typedef when declaring an enum in C++?
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In C, declaring your enum the first way allows you to use it like so:
TokenType my_type;
If you use the second style, you'll be forced to declare your variable like this:
enum TokenType my_type;
As mentioned by others, this doesn't make a difference in C++. M...
How to sum array of numbers in Ruby?
... using array.map(...).inject(...) is inefficient, you will iterate through all data twice. Try array.inject(0) { |sum, product| sum += product.price }
– everett1992
Apr 4 '13 at 6:11
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How can I auto-elevate my batch file, so that it requests from UAC administrator rights if required?
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You can have the script call itself with psexec's -h option to run elevated.
I'm not sure how you would detect if it's already running as elevated or not... maybe re-try with elevated perms only if there's an Access Denied error?
Or, you could simp...
Is there a HTML opposite to ?
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Not allowed in the xhtml standard at least.
– Dykam
Aug 4 '09 at 19:56
29
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How can I get rid of an “unused variable” warning in Xcode?
...as an "unused" attribute you can use to suppress that warning:
BOOL saved __attribute__((unused)) = [moc save:&error];
Alternatively (in case LLVM doesn't support the above), you could split the variable declaration into a separate line, guaranteeing that the variable would be "used" whether ...
How to print the full NumPy array, without truncation?
...ld instead of a.size <= _summaryThreshold, and np.nan returns False for all >/</>=/<= comparisons. 'nan' only happens to work due to fragile implementation details of Python 2's mixed-type comparison logic; it breaks completely on Python 3.
– user2357112 supports...
Executing Batch File in C#
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Thanks! now i actually can see what the error is. "C:\Windows\System32\txtmanipulator.bat is not recognized as an internal or external command, program or batchfile" (Translated from dutch) Which is odd. Because when i run txtmanipulator from ...
Computed / calculated / virtual / derived columns in PostgreSQL
...(Not in Postgres 13, yet) .
Related:
Attribute notation for function call gives error
Until then, you can emulate VIRTUAL generated columns with a function using attribute notation (tbl.col) that looks and works much like a virtual generated column. That's a bit of a syntax oddity which exi...