大约有 40,000 项符合查询结果（耗时：0.0331秒） [XML]
Why does comparing strings using either '==' or 'is' sometimes produce a different result?
...s and dynamic
programming language runtimes) that
rely heavily on hash tables with
string keys. Without interning,
checking that two different strings
are equal involves examining every
character of both strings. This is
slow for several reasons: it is
inherently O(n) in the length o...
MySQL - Rows to Columns
...e of terms that I'll use for the rest of this post. This will be the base table:
select * from history;
+--------+----------+-----------+
| hostid | itemname | itemvalue |
+--------+----------+-----------+
| 1 | A | 10 |
| 1 | B | 3 |
| 2 | A | ...
What is SELF JOIN and when would you use it? [duplicate]
...
You use a self join when a table references data in itself.
E.g., an Employee table may have a SupervisorID column that points to the employee that is the boss of the current employee.
To query the data and get information for both people in one row,...
Thread-safe List property
...em.ServiceModel.dll (which is part of the client profile but not of the portable class library).
Hope that helps.
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What's the difference between django OneToOneField and ForeignKey?
....title
Run python manage.py syncdb to execute the sql code and build the tables for your app in your database. Then use python manage.py shell to open a python shell.
Create the Reporter object R1.
In [49]: from thepub.models import Reporter, Article
In [50]: R1 = Reporter(first_name='Rick')
I...
Create a .csv file with values from a Python list
...mns if each element is a list as well. This is pretty handy for outputting tables.
– whatnick
Oct 7 '14 at 5:22
6
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How to implement the activity stream in a social network
...rowse far back in time (if you even offer this)
I use a plain old MySQL table for dealing with about 15 million activities.
It looks something like this:
id
user_id (int)
activity_type (tinyint)
source_id (int)
parent_id (int)
parent_type (tinyint)
time (...
Detect Windows version in .net
...nment is running in, check out this library.
Important note: if your executable assembly manifest doesn't explicitly state that your exe assembly is compatible with Windows 8.1 and Windows 10.0, System.Environment.OSVersion will return Windows 8 version, which is 6.2, instead of 6.3 and 10.0! Sourc...
How to resize Twitter Bootstrap modal dynamically based on the content
... of the above worked.
.modal-dialog{
position: relative;
display: table; /* This is important */
overflow-y: auto;
overflow-x: auto;
width: auto;
min-width: 300px;
}
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How to delete from multiple tables in MySQL?
I am trying to delete from a few tables at once. I've done a bit of research, and came up with this
7 Answers
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