大约有 374 项符合查询结果（耗时：0.0348秒） [XML]
Accessing outside variable using anonymous function as params
...hat function is executing.
Code:
$result = '';
fetch("SELECT title FROM tbl", function($r) use (&$result) {
$result .= $r['title'];
});
But beware (taken from one of comments in previous link):
use() parameters are early binding - they use the variable's value at
the point where t...
How to sum a variable by group
...
library(plyr)
ddply(tbl, .(Category), summarise, sum = sum(Frequency))
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How can I return pivot table output in MySQL?
...OUNT(action = 'PRINT' AND pagecount = 3 OR NULL) AS "Print 3 pages"
FROM tbl
GROUP BY company_name;
SQL Fiddle.
How?
TRUE OR NULL yields TRUE.
FALSE OR NULL yields NULL.
NULL OR NULL yields NULL.
And COUNT only counts non-null values. Voilá.
...
PostgreSQL function for last inserted ID
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SELECT CURRVAL(pg_get_serial_sequence('my_tbl_name','id_col_name'))
You need to supply the table name and column name of course.
This will be for the current session / connection
http://www.postgresql.org/docs/8.3/static/functions-sequence.html
...
Relational table naming convention [closed]
... it is a column. The same goes for tables. Don't name tables EMPLOYEE_T or TBL_EMPLOYEES because the second it is replaced with a view, things get really confusing.
Don't embed type information in names, such as "vc_firstname" for varchar, or "flavour_enum". Also don't embed constraints in column n...
What is the difference between a port and a socket?
...eferences
TCP-IP Illustrated Volume 1 The Protocols, W. Richard Stevens, 1994 Addison Wesley
RFC793, Information Sciences Institute, University of Southern California for DARPA
RFC147, The Definition of a Socket, Joel M. Winett, Lincoln Laboratory
...
How do you set a default value for a MySQL Datetime column?
...I am using version 5.6.22, but still I got error as follows : CREATE TABLE tbl ( InsertDate DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP, UpdateDate TIMESTAMP NULL ON UPDATE CURRENT_TIMESTAMP(6) ); Error Code: 1294. Invalid ON UPDATE clause for 'UpdateDate' column
– Manish S...
What is in your Mathematica tool bag? [closed]
...at style of hack for "wrapping" a
built-in function was invented around 1994 by Robby Villegas and I,
ironically for the function Message, in a package called ErrorHelp
that I wrote for the Mathematica Journal back then. It has been used
many times, by many people, since then. It's a bit...
TCP 的那些事儿（下） - 更多技术 - 清泛网 - 专注C/C++及内核技术
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其它拥塞控制算法简介
TCP Vegas 拥塞控制算法
这个算法1994年被提出，它主要对TCP Reno 做了些修改。这个算法通过对RTT的非常重的监控来计算一个基准RTT。然后通过这个基准RTT来估计当前的网络实际带宽，如果实际带宽比我们...
How do I add a foreign key to an existing SQLite table?
...un a query like the following: SELECT type, sql FROM
sqlite_master WHERE tbl_name='X'.
Use CREATE TABLE to construct a new table "new_X" that is in the
desired revised format of table X. Make sure that the name "new_X"
does not collide with any existing table name, of course.
Transfer cont...