大约有 36,200 项符合查询结果（耗时：0.0372秒） [XML]
Random record in ActiveRecord
...del.first(:offset => offset)
To be honest, I've just been using ORDER BY RAND() or RANDOM() (depending on the database). It's not a performance issue if you don't have a performance issue.
share
|
...
How can I get the list of a columns in a table for a SQLite database?
...s called the data dictionary. In sqlite a list of all tables can be found by querying sqlite_master table (or view?)
sqlite> create table people (first_name varchar, last_name varchar, email_address varchar);
sqlite> select * from sqlite_master;
table|people|people|2|CREATE TABLE people (fir...
Why should C++ programmers minimize use of 'new'?
...struct called a destructor. This mechanism allows you to manage resources by aligning the lifetime of the resource with the lifetime of a variable. This technique is called RAII and is the distinguishing point of C++. It "wraps" resources into objects. std::string is a perfect example. This snipp...
How to subtract X days from a date using Java calendar?
... subtract 5 days from the current time of the calendar, you can achieve it by calling:
Calendar calendar = Calendar.getInstance(); // this would default to now
calendar.add(Calendar.DAY_OF_MONTH, -5).
share
|
...
(Deep) copying an array using jQuery [duplicate]
... length of an array that holds the context for the method always decreases by 1 and is edited in place.
– danronmoon
Jun 5 '12 at 2:27
...
What is the difference between gmake and make?
... make implementations of various commercial unixes.
The language accepted by GNU make is a superset of the one supported by the traditional make utility.
By using 'gmake' specifically you can use GNU make extensions without worrying about them being misinterpreted by some other make implementation...
How to find gaps in sequential numbering in mysql?
...h line). 1st query: 2812 rows in set (1 min 31.09 sec). Made another table by selecting distinct order numbers. Your query without my repeats: 1009 rows in set (18.04 sec)
– Chris K
Jun 6 '13 at 19:54
...
Hibernate, @SequenceGenerator and allocationSize
...nate when using @SequenceGenerator - it increases real database sequence by one , multiple this value by 50 (default allocationSize value) - and then uses this value as entity ID.
...
dplyr: “Error in n(): function should not be called directly”
...
As mentioned by the previous answer, you may have a conflict between plyr and dplyr. You can to run this command to unload the plyr package.
detach("package:plyr", unload=TRUE)
Then you can continue as expected.
library(dplyr)
...
...
What are the functional differences between NW.js, Brackets-Shell and Electron?
.... They are very clear that "The brackets-shell is only maintained for use by the Brackets project ", that screams run away to me.
https://github.com/adobe/brackets-shell#overview
Atom-shell seems to be recently active, but it seems much like brackets in that they are really writing and editor/IDE...