大约有 41,000 项符合查询结果（耗时：0.0387秒） [XML]
Left Join With Where Clause
...ring away rows where the left join doesn't succeed. Move it to the join:
SELECT `settings`.*, `character_settings`.`value`
FROM `settings`
LEFT JOIN
`character_settings`
ON `character_settings`.`setting_id` = `settings`.`id`
AND `character_settings`.`character_id` = '1'
...
What is the largest Safe UDP Packet Size on the Internet
...
It is true that a typical IPv4 header is 20 bytes, and the UDP header is 8 bytes. However it is possible to include IP options which can increase the size of the IP header to as much as 60 bytes. In addition, sometimes it is necessary for intermedia...
SQL SELECT speed int vs varchar
...k: A=261MB B=292MB C=322MB
Non-indexed by id: select count(*), select by id: 450ms same on all tables
Insert* one row per TX: B=9ms/record C=9ms/record
Bulk insert* in single TX: B=140usec/record C=180usec/record
Indexed by id, select by id: B=about 2...
java.net.ConnectException: localhost/127.0.0.1:8080 - Connection refused
...ly i am doing the same thing. Can u explain in detail. Where to change the ip address to 10.0.2.2. This is the folder i am trying to access from xampp server localhost:8080/aero
– pradeep
Mar 31 '11 at 5:56
...
Listing all permutations of a string/integer
...(IEnumerable<T> list, int length)
{
if (length == 1) return list.Select(t => new T[] { t });
return GetPermutations(list, length - 1)
.SelectMany(t => list.Where(e => !t.Contains(e)),
(t1, t2) => t1.Concat(new T[] { t2 }));
}
Example:
IEnumerable<...
从一个开发的角度看负载均衡和LVS - 更多技术 - 清泛网 - 专注C/C++及内核技术
...P/UDP，LVS支持TCP/UDP的负载均衡。
LVS的转发主要通过修改IP地址（NAT模式，分为源地址修改SNAT和目标地址修改DNAT）、修改目标MAC（DR模式）来实现。
那么为什么LVS是在第四层做负载均衡？
首先LVS不像HAProxy等七层软负载面...
How can I do DNS lookups in Python, including referring to /etc/hosts?
...y sure if you want to do DNS lookups yourself or if you just want a host's ip. In case you want the latter,
import socket
print(socket.gethostbyname('localhost')) # result from hosts file
print(socket.gethostbyname('google.com')) # your os sends out a dns query
...
List of standard lengths for database fields
...ize for names in your
database. In particular, do not assume that a four-character
Japanese name in UTF-8 will fit in four bytes – you are likely to
actually need 12.
https://www.w3.org/International/questions/qa-personal-names
For database fields, VARCHAR(255) is a safe default choic...
How does the socket API accept() function work?
The socket API is the de-facto standard for TCP/IP and UDP/IP communications (that is, networking code as we know it). However, one of its core functions, accept() is a bit magical.
...
Oracle SELECT TOP 10 records
I have an big problem with an SQL Statement in Oracle. I want to select the TOP 10 Records ordered by STORAGE_DB which aren't in a list from an other select statement.
...