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differentiate null=True, blank=True in django
...e)
The database fields created for PostgreSQL 9.4 are :
CREATE TABLE Test (
id serial NOT NULL,
"charNull" character varying(10),
"charBlank" character varying(10) NOT NULL,
"charNullBlank" character varying(10),
"intNull" in...
How to get the top 10 values in postgresql?
... *,
rank() over (order by some_value_column desc) as my_rank
from mytable) subquery
where my_rank <= 10
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Why is it slower to iterate over a small string than a small list?
... just
9 LOAD_CONST 6 (('a', 'b', 'c'))
as tuples are immutable. Test:
>>> python3 -m timeit '[x for x in ("a", "b", "c")]'
1000000 loops, best of 3: 0.369 usec per loop
Great, back up to speed.
For Python 2:
def list_iterate():
[item for item in ["a", "b", "c"]]
...
Repository Pattern Step by Step Explanation [closed]
...are persisted. All of the knowledge of persistence, including mapping from tables to objects, is safely contained in the repository.
Very often, you will find SQL queries scattered in the codebase and when you come to add a column to a table you have to search code files to try and find usages of a...
Virtual member call in a constructor
...y are constructed, but start out as the most derived type, with the method table being for the most derived type. This means that virtual method calls always run on the most derived type.
When you combine these two facts you are left with the problem that if you make a virtual method call in a cons...
Creating stored procedure and SQLite?
...
Yet, it is possible to fake it using a dedicated table, named for your fake-sp, with an AFTER INSERT trigger. The dedicated table rows contain the parameters for your fake sp, and if it needs to return results you can have a second (poss. temp) table (with name related to t...
Difference between filter and filter_by in SQLAlchemy
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These code examples are misleading: Declarative base table classes and instances have neither filter nor query methods; they use the session.
– Turtles Are Cute
Mar 16 '16 at 19:45
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Differences between MySQL and SQL Server [closed]
...
I can't believe that no one mentioned that MySQL doesn't support Common Table Expressions (CTE) / "with" statements. It's a pretty annoying difference.
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Postgresql query between date ranges
...= 2
This involves calculating the conditions for every single row in the table (a scan) and not using index to find the range of rows that will match (a range-seek).
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Imitating a blink tag with CSS3 animations
... +animation(blink 1s 0s reverse infinite)
+transform(translateZ(0))
.table
display: table
height: 5em
width: 100%
vertical-align: middle
.cell
display: table-cell
width: 100%
height: 100%
vertical-align: middle
http://codepen.io/anon/pen/kaGxC (sass with bourbon)
...