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How to avoid “RuntimeError: dictionary changed size during iteration” error?
...n you want to delete an object in inner dict. for example you have a dic A and dict B in dict A. if you want to delete object in dict B it occurs error
– Ali-T
Apr 18 at 6:35
1
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SQLAlchemy: cascade delete
...ession.query().filter().delete() (which doesn't put elements in the memory and deletes directly from db).
Using this method sqlalchemy's cascade='all, delete' doesn't work. There is a solution though: ON DELETE CASCADE through db (note: not all databases support it).
class Child(Base):
__table...
Update multiple rows in same query using PostgreSQL
...
You can also use update ... from syntax and use a mapping table. If you want to update more than one column, it's much more generalizable:
update test as t set
column_a = c.column_a
from (values
('123', 1),
('345', 2)
) as c(column_b, column_a)
wher...
SQL Server Index Naming Conventions [closed]
Is there some standard way to name indexes for SQL Server? It seems that the primary key index is named PK_ and non-clustered indexes typically start with IX_. Are there any naming conventions beyond that for unique indexes?
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Why do I get an UnsupportedOperationException when trying to remove an element from a List?
...|")
On better algorithm
Instead of calling remove one at a time with random indices, it's better to generate enough random numbers in the range, and then traversing the List once with a listIterator(), calling remove() at appropriate indices. There are questions on stackoverflow on how to gener...
How can I change the thickness of my tag
...
For consistency remove any borders and use the height for the <hr> thickness. Adding a background color will style your <hr> with the height and color specified.
In your stylesheet:
hr {
border: none;
height: 1px;
/* Set the hr color ...
ThreadStart with parameters
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What is myParamObject and myUrl?
– dialex
Mar 14 '12 at 17:26
3
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Sleep for milliseconds
...
Note that there is no standard C API for milliseconds, so (on Unix) you will have to settle for usleep, which accepts microseconds:
#include <unistd.h>
unsigned int microseconds;
...
usleep(microseconds);
...
Force drop mysql bypassing foreign key constraint
I'm trying to delete all tables from a database except one, and I end up having the following error:
6 Answers
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Is Enabling Double Escaping Dangerous?
...ath.
Finally, a very simple, if limited workaround is simply to avoid '+' and use '%20' instead. In any case, using the '+' symbol to encode a space is not valid url encoding, but specific to a limited set of protocols and probably widely supported for backwards-compatibility reasons. If only for...