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libevent对比libev的基准测试 - C/C++ - 清泛网 - 专注C/C++及内核技术
...libevent 每次迭代的总时间增加得快得多，无论客户端数量如何，花费的时间几乎是 libev 的两倍。不过，两者都表现出相似的增长特征。
轮询时间也非常相似，libevent 在 1000-fd 情况下始终较慢，而在 100-fd 情况下，时间几乎相同...
MySQL integer field is returned as string in PHP
...
When you select data from a MySQL database using PHP the datatype will always be converted to a string. You can convert it back to an integer using the following code:
$id = (int) $row['userid'];
Or by using the function intval():
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How to combine two or more querysets in a Django view?
...s. For example:
>>> qs1.union(qs2, qs3)
The UNION operator selects only distinct values by default. To allow duplicate values, use the all=True
argument.
union(), intersection(), and difference() return model instances of
the type of the first QuerySet even if the arguments ...
Generating a random & unique 8 character string using MySQL
...umn:
INSERT INTO vehicles VALUES (blah); -- leaving out the number plate
SELECT @lid:=LAST_INSERT_ID();
UPDATE vehicles SET numberplate=concat(
substring('ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789', rand(@seed:=round(rand(@lid)*4294967296))*36+1, 1),
substring('ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789'...
Select count(*) from multiple tables
How can I select count(*) from two different tables (call them tab1 and tab2 ) having as result:
18 Answers
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Error installing mysql2: Failed to build gem native extension
I am having some problems when trying to install mysql2 gem for Rails. When I try to install it by running bundle install or gem install mysql2 it gives me the following error:
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Union Vs Concat in Linq
...ence is not changed.
If you will override Equals and GetHashCode (used to select distinct items), then items will not be compared by reference:
class X
{
public int ID { get; set; }
public override bool Equals(object obj)
{
X x = obj as X;
if (x == null)
re...
How do I import CSV file into a MySQL table?
...
You have to select a table before you can continue... and since the whole point is not having to make the table...
– Dominique
Nov 4 '14 at 20:06
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Mysql - How to quit/exit from stored procedure
...RE v_workflow_count INT(10);
-- checking if workflow created for package
select count(*) INTO v_workflow_count from workflow w where w.package_id =
package_id ;
this_proc:BEGIN -- this_proc block start here
IF v_workflow_count = 0 THEN
select 'no work flow ' as 'workflow_status' ;
...
Grant **all** privileges on database
...ly you are in database db_name and then execute the commands like create , select and insert operations.
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