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updating table rows in postgres using subquery
...
Postgres allows:
UPDATE dummy
SET customer=subquery.customer,
address=subquery.address,
partn=subquery.partn
FROM (SELECT address_id, customer, address, partn
FROM /* big hairy SQL */ ...) AS subquery
WHERE dummy.addre...
Linq to Entities join vs groupjoin
...groups. This can be turned into a flat list of parent-child pairs by two small additions:
from p in parents
join c in children on p.Id equals c.Id into g // <= into
from c in g.DefaultIfEmpty() // <= flattens the groups
select new { Parent = p.Value, Child = c?.ChildValue }
The ...
Which is generally best to use — StringComparison.OrdinalIgnoreCase or StringComparison.InvariantCul
...onsider using a new set of String overloads in Microsoft .NET 2.0. Specifically, data that is designed to be culture-agnostic and linguistically irrelevant should begin specifying overloads using either the StringComparison.Ordinal or StringComparison.OrdinalIgnoreCase members of the new StringCompa...
How can you diff two pipelines in Bash?
...dev/fd/63 to get a filename that the command can open and read from to actually read from an already-open file descriptor that bash set up before exec'ing the command. (i.e. bash uses pipe(2) before fork, and then dup2 to redirect from the output of quux to an input file descriptor for diff, on fd ...
What is the difference between CMD and ENTRYPOINT in a Dockerfile?
...ypoint. i.e., the actual thing that gets executed is /bin/sh -c bash. This allowed Docker to implement RUN quickly by relying on the shell's parser.
Later on, people asked to be able to customize this, so ENTRYPOINT and --entrypoint were introduced.
Everything after ubuntu in the example above is ...
Add unique constraint to combination of two columns
...ctive, PersonNumber)
VALUES(N'foo', 1, 22);
GO
Data in the table after all of this:
ID Name Active PersonNumber
---- ------ ------ ------------
1 foo 1 22
2 foo 0 22
Error message on the last insert:
Msg 2627, Level 14, State 1, Line 3
Violation of UNIQUE KEY c...
When serving JavaScript files, is it better to use the application/javascript or application/x-javas
...r js in your pages, IE7 and IE8 will not run your script! Blame Microsoft all you want, but if you want most people to run your pages use text/javascript.
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How to use sed to replace only the first occurrence in a file?
...lude directive before any existing #includes. For this sort of task, I normally use a small bash script with sed to re-write the file.
...
string c_str() vs. data()
... have seen in actual implementations, they either do the same or data() calls c_str() .
6 Answers
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C++ equivalent of Java's toString?
...n case your operator<< wants to print out internals of class A and really needs access to its private and protected members you could also declare it as a friend function:
class A {
private:
friend std::ostream& operator<<(std::ostream&, const A&);
int j;
};
std::ostrea...