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What are the basic rules and idioms for operator overloading?
...t version.
For the -> operator, if value_type is of class (or struct or union) type, another operator->() is called recursively, until an operator->() returns a value of non-class type.
The unary address-of operator should never be overloaded.
For operator->*() see this question. It's ...
Count Rows in Doctrine QueryBuilder
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Example working with grouping, union and stuff.
Problem:
$qb = $em->createQueryBuilder()
->select('m.id', 'rm.id')
->from('Model', 'm')
->join('m.relatedModels', 'rm')
->groupBy('m.id');
For this to work possible sol...
How does Amazon RDS backup/snapshot actually work?
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We also run several RDS instances, in addition to MySQL on some machines that we manage ourselves. I can't comment specifically, as I'm not an Amazon engineer, but several things I've learned that might explain what you're seeing:
Although Amazon does not share the backend...
How do I return rows with a specific value first?
...L Server, but that's because the syntax is non-standard and only works for MySQL. When using a CASE statement (which is standard SQL) SQL Server can very well use an expression in the ORDER BY clause. "too stupid to process equivalency tests" is simply wrong. If at all it should read: "does not supp...
How do you do a limit query in JPQL or HQL?
In Hibernate 3, is there a way to do the equivalent of the following MySQL limit in HQL?
14 Answers
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how to emulate “insert ignore” and “on duplicate key update” (sql merge) with postgresql?
...skipped if it would violate a primary/unique key constraint. For instance, MySQL has INSERT IGNORE .
11 Answers
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How do I convert this list of dictionaries to a csv file?
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set().union(*(d.keys() for d in mylist)) to get all the keys in the list (if you have some which don't have all the keys.)
– Julian Camilleri
Nov 13 '18 at 10:00
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“use database_name” command in PostgreSQL
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If I'm not mistaken, databases in MySQL are more akin to schemas in PostgreSQL -- you can switch between those, but DBs in PostgreSQL are a whole different ballgame.
– mpen
May 10 '12 at 3:40
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Extract a dplyr tbl column as a vector
...masked from 'package:base':
#>
#> intersect, setdiff, setequal, union
db <- src_sqlite(tempfile(), create = TRUE)
iris2 <- copy_to(db, iris)
vec <- pull(iris2, Species)
head(vec)
#> [1] "setosa" "setosa" "setosa" "setosa" "setosa" "setosa"
...
Is there a way to filter network requests using Google Chrome developer tools?
... png files smaller than 100kb in network panel
see DevTools: State Of The Union 2015 by Addy Osmani
Since Chrome 42.
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