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postgresql - sql - count of `true` values
...his works:
SELECT count(*) AS total
, sum(myCol::int) AS countTrue --convert Boolean to Integer
FROM yourTable
;
or better (to avoid :: and use standard SQL syntax):
SELECT count(*) AS total
, sum(CAST(myCol AS int)) AS countTrue --convert Boolean to Integer
FROM yourTable
;
...
How to properly check if std::function is empty in C++11?
... an empty lambda doesn't really make sense. Behind the scenes the compiler converts a lambda expression into a struct (or class) definition, with the variables you capture stored as data members of this struct. A public function call operator is also defined, which is what allows you to invoke the l...
Type converting slices of interfaces
I'm curious why Go does't implicitly convert []T to []interface{} when it will implicitly convert T to interface{} . Is there something non-trivial about this conversion that I'm missing?
...
Explaining Python's '__enter__' and '__exit__'
...ptional case is handled here
exc = False
if not exit(mgr, *sys.exc_info()):
raise
# The exception is swallowed if exit() returns true
finally:
# The normal and non-local-goto cases are handled here
if exc:
exit(mgr, None, None, None)
try some cod...
How to use XPath in Python?
...("//*")
if len(res) != 2:
print "xpath query: wrong node set size"
sys.exit(1)
if res[0].name != "doc" or res[1].name != "foo":
print "xpath query: wrong node set value"
sys.exit(1)
doc.freeDoc()
ctxt.xpathFreeContext()
Sample of ElementTree XPath Use
from elementtree.ElementTre...
Default template arguments for function templates
...
On Windows, with all versions of Visual Studio you can convert this error (C4519) to a warning or disable it like so:
#ifdef _MSC_VER
#pragma warning(1 : 4519) // convert error C4519 to warning
// #pragma warning(disable : 4519) // disable error C4519
#endif
See more details ...
Fastest way to determine if an integer's square root is an integer
...
Wow! I'll try to convert this to Java and do a comparison, as well as an accuracy check on the results. I'll let you know what I find.
– Kip
Jan 12 '09 at 21:47
...
ERROR: Error 1005: Can't create table (errno: 121)
...rch for these orphan tables with:
SELECT * FROM INFORMATION_SCHEMA.INNODB_SYS_TABLES WHERE NAME LIKE '%#sql%';
The version I was working with was 5.1, but the above command only works on versions >= 5.6 (manual is incorrect about it working for 5.5 or earlier, because INNODB_SYS_TABLES does no...
Convert character to ASCII code in JavaScript
How can I convert a character to its ASCII code using JavaScript?
10 Answers
10
...
Convert decimal to hexadecimal in UNIX shell script
In a UNIX shell script, what can I use to convert decimal numbers into hexadecimal? I thought od would do the trick, but it's not realizing I'm feeding it ASCII representations of numbers.
...