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MySQL Cannot drop index needed in a foreign key constraint
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You have to drop the foreign key. Foreign keys in MySQL automatically create an index on the table (There was a SO Question on the topic).
ALTER TABLE mytable DROP FOREIGN KEY mytable_ibfk_1 ;
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How to get Scala List from Java List?
...now built into the language using:
import scala.collection.JavaConversions._
...
lst.toList.foreach{ node => .... }
works. asScala did not work
In 2.12.x use import scala.collection.JavaConverters._
In 2.13.x use import scala.jdk.CollectionConverters._
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Combining INSERT INTO and WITH/CTE
...ions go at the top.
Wrapping every insert in a CTE has the benefit of visually segregating the query logic from the column mapping.
Spot the mistake:
WITH _INSERT_ AS (
SELECT
[BatchID] = blah
,[APartyNo] = blahblah
,[SourceRowID] = blahblahblah
FROM Table1 AS t1
)
INSERT ...
What's the difference between ViewData and ViewBag?
...y typed view models (the same way as viewdata should be avoided).
So basically it replaces magic strings:
ViewData["Foo"]
with magic properties:
ViewBag.Foo
for which you have no compile time safety.
I continue to blame Microsoft for ever introducing this concept in MVC.
The name of the pro...
Checking for a dirty index or untracked files with Git
...din, command line options, arguments, etc. will produce the same output in all versions of Git where the command/option exists). New output variations in plumbing commands can be introduced via new options, but that can not introduce any problems for programs that have already been written against o...
C++ convert hex string to signed integer
...>> x;
// output it as a signed type
std::cout << static_cast<int>(x) << std::endl;
}
In the new C++11 standard, there are a few new utility functions which you can make use of! specifically, there is a family of "string to number" functions (http://en.cppreference.c...
Traits vs. interfaces
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Except that traits are not interfaces at all. Interfaces are specification that can be checked against. Traits cannot be checked against, hence they are implementation only. They are the exact opposite of interfaces. That line in the RFC is simply wrong...
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SQLAlchemy: how to filter date field?
...In fact, your query is right except for the typo: your filter is excluding all records: you should change the <= for >= and vice versa:
qry = DBSession.query(User).filter(
and_(User.birthday <= '1988-01-17', User.birthday >= '1985-01-17'))
# or same:
qry = DBSession.query(User)....
MongoDB not equal to
...b.inventory.find( { price: { $not: { $gt: 1.99 } } } )
That would select all documents where:
The price field value is less than or equal to 1.99 or the price
Field does not exist
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How to access component methods from “outside” in ReactJS?
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class Parent extends React.Class {
constructor(props) {
this._child = React.createRef();
}
componentDidMount() {
console.log(this._child.current.someMethod()); // Prints 'bar'
}
render() {
return (
<div>
<Child ref=...