大约有 42,000 项符合查询结果（耗时：0.0371秒） [XML]
Sorting 1 million 8-decimal-digit numbers with 1 MB of RAM
...W3520. You can verify that the program works using the following Python script, assuming a program name of sort1mb.exe.
from subprocess import *
import random
sequence = [random.randint(0, 99999999) for i in xrange(1000000)]
sorter = Popen('sort1mb.exe', stdin=PIPE, stdout=PIPE)
for value in sequ...
Postgres manually alter sequence
...
The parentheses are misplaced:
SELECT setval('payments_id_seq', 21, true); # next value will be 22
Otherwise you're calling setval with a single argument, while it requires two or three.
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Rails 3: Get Random Record
...You can use the following trick on an indexed column (PostgreSQL syntax):
select *
from my_table
where id >= trunc(
random() * (select max(id) from my_table) + 1
)
order by id
limit 1;
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Run PostgreSQL queries from the command line
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psql -U username -d mydatabase -c 'SELECT * FROM mytable'
If you're new to postgresql and unfamiliar with using the command line tool psql then there is some confusing behaviour you should be aware of when you've entered an interactive session.
For example, ...
MySQL select 10 random rows from 600K rows fast
How can I best write a query that selects 10 rows randomly from a total of 600k?
26 Answers
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IIS7 Permissions Overview - ApplicationPoolIdentity
...eplace this text below if it is named differently)
Open Windows Explorer
Select a file or directory.
Right click the file and select "Properties"
Select the "Security" tab
Click the "Edit" and then "Add" button
Click the "Locations" button and make sure you select the local machine. (Not the Windo...
Looping over arrays, printing both index and value
...="snoopy"
bar[bar]="nice"
bar[baz]="cool"
Issue with newlines or special chars
Unfortunely, there is at least one condition making this not work anymore: when variable do contain newline:
foo[17]=$'There is one\nnewline'
Command paste will merge line-by-line, so output will become wrong:
past...
Get a list of checked checkboxes in a div using jQuery
I want to get a list of names of checkboxes that are selected in a div with certain id. How would I do that using jQuery?
8...
Fastest way to check if a file exist using standard C++/C++11/C?
...r. This does not use many fancy features of C++:
bool is_file_exist(const char *fileName)
{
std::ifstream infile(fileName);
return infile.good();
}
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SQL Server loop - how do I loop through a set of records
how do I loop through a set of records from a select?
8 Answers
8
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