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How to use NULL or empty string in SQL
...
Select *
From Table
Where (col is null or col = '')
Or
Select *
From Table
Where IsNull(col, '') = ''
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improve t...
记一次MongoDB性能问题 - 大数据 & AI - 清泛网 - 专注C/C++及内核技术
...使用ext3，可能会遇到这类问题，所以还是大概介绍一下如何解决：
MongoDB按需自动生成数据文件：先是<DB>.0，大小是64M，然后是<DB>.1，大小翻番到128M，到了<DB>.5，大小翻番到2G，其后的数据文件就保持在2G大小。为了避免可能出...
phpcms v9与ucenter通信失败 完美解决 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...名：root （必填，视实际情况而定）
Ucenter 数据库密码：root （视实际情况而定）
Ucenter 数据库名：discuz （必填，视实际情况而定）
Ucenter 数据库表前缀：`discuz`.pre_ucenter_ （必填，视实际情况而定。如果此...
How to secure database passwords in PHP?
...in your httpd.conf or virtual hosts file file. If you do that you can call mysql_connect() with no parameters, which means PHP will never ever output your information.
This is how you specify these values in those files:
php_value mysql.default.user myusername
php_value mysql.default.password...
Quick easy way to migrate SQLite3 to MySQL? [closed]
Anyone know a quick easy way to migrate a SQLite3 database to MySQL?
17 Answers
17
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Why use the SQL Server 2008 geography data type?
...tance < 500 * 1609.344
orderby distance
select f;
return q1.FirstOrDefault();
}
Then there is a very good reason to use Geography.
Explanation of spatial within Entity Framework.
Updated with Creating High Performance Spatial Databases
As I noted on Noe...
Pythonic way to create a long multi-line string
...de commas between the string segments, then it will be a tuple.
query = ('SELECT action.descr as "action", '
'role.id as role_id,'
'role.descr as role'
' FROM '
'public.role_action_def,'
'public.role,'
'public.record_def, '
'public.ac...
Amazon EC2, mysql aborting start because InnoDB: mmap (x bytes) failed; errno 12
...EC2 Linux Micro instance. Since Micro instances have only 613MB of memory, MySQL crashed every now and then. After a long search about MySQL, Micro Instance and Memory Managment I found out there is no default SWAP space for Micro instance. So if you want to avoid the crash you may need to setup a s...
Is there any difference between GROUP BY and DISTINCT
...CT and distinct by UNION cause an oracle error, but GROUP BY worked; I was selecting only 1 column from a view and not using any aggregation; I'm still baffled why it required it, but it does confirm there is some difference in the execution. As others point out, it also lets you GROUP BY columns no...
java中的缓存技术该如何实现 - 更多技术 - 清泛网 - 专注C/C++及内核技术
java中的缓存技术该如何实现1缓存为什么要存在?2缓存可以存在于什么地方?3缓存有哪些属性?4缓存介质?搞清楚这4个问题,那么我们就可以随意的通过应用的场景来判断使用何...1、缓存为什么要存在？
2、缓存可以存在于什么地方...