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What is the “N+1 selects problem” in ORM (Object-Relational Mapping)?
... I understand that it has something to do with having to make a lot of database queries for something that seems simple in the object world.
...
Starting python debugger automatically on error
...
You can use traceback.print_exc to print the exceptions traceback. Then use sys.exc_info to extract the traceback and finally call pdb.post_mortem with that traceback
import pdb, traceback, sys
def bombs():
a = []
print a[0]
if __name__ == '...
Oracle “(+)” Operator
...e a link at the official Oracle documentation: docs.oracle.com/html/A95915_01/sqopr.htm
– Vargan
Jun 3 '15 at 16:55
...
What is the difference between a field and a property?
...It is private to your class and stores the actual data.
private string _myField;
// this is a property. When accessed it uses the underlying field,
// but only exposes the contract, which will not be affected by the underlying field
public string MyProperty
{
get
...
Confused about stdin, stdout and stderr?
...
64
It would be more correct to say that stdin, stdout, and stderr are "I/O streams" rather
than fi...
Python list subtraction operation
...t to use the - infix syntax, you can just do:
class MyList(list):
def __init__(self, *args):
super(MyList, self).__init__(args)
def __sub__(self, other):
return self.__class__(*[item for item in self if item not in other])
you can then use it like:
x = MyList(1, 2, 3, 4...
Google Tag Manager 入门指南 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...页脚，如：footer.inc：
<script type=”text/javascript”>
var _gaq = _gaq || [];
_gaq.push(["_setAccount", "UA-XXXXXX-1"]);
_gaq.push(["_trackPageview"]);
(function() {
var ga = document.createElement(“script”); ga.type = “text/javascript”; ga.async = true;
ga.src = (...
Elegant way to invert a map in Scala
...
Assuming values are unique, this works:
(Map() ++ origMap.map(_.swap))
On Scala 2.8, however, it's easier:
origMap.map(_.swap)
Being able to do that is part of the reason why Scala 2.8 has a new collection library.
...
How to remove multiple indexes from a list at the same time? [duplicate]
...obody suggested this as a solution is that this creates a new list object (based on the contents of the original) rather than actually modifying the original list object. Since the end result is similar, I'll upvote your answer. Welcome to Stack Exchange.
– Anthony Geoghegan
...
How do I spool to a CSV formatted file using SQLPLUS?
... numbers (avoid scientific notation on IDs)
spool myfile.csv
select table_name, tablespace_name
from all_tables
where owner = 'SYS'
and tablespace_name is not null;
Output will be like:
TABLE_PRIVILEGE_MAP ,SYSTEM
SYSTEM_PRIVILEGE_MAP ,S...