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MySQL: Insert record if not exists in table
...tnames (name, address, tele)
SELECT * FROM (SELECT 'Rupert', 'Somewhere', '022') AS tmp
WHERE NOT EXISTS (
SELECT name FROM table_listnames WHERE name = 'Rupert'
) LIMIT 1;
Query OK, 1 row affected (0.00 sec)
Records: 1 Duplicates: 0 Warnings: 0
SELECT * FROM `table_listnames`;
+----+------...
What are the special dollar sign shell variables?
...ipeline exit status.
$! is the PID of the most recent background command.
$0 is the name of the shell or shell script.
Most of the above can be found under Special Parameters in the Bash Reference Manual. There are all the environment variables set by the shell.
For a comprehensive index, please ...
Android phone orientation overview including compass
...ow I think (hope) I have a better feeling for it again but I am still not 100%. I will try and explain my patchy understanding of it and hopefully people will be able to correct me if I am wrong in parts or fill in any blanks.
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OceanBase使用libeasy原理源码分析：服务器端 - 数据库(内核) - 清泛网 - ...
...y基于libev，对libev不了解的参见 这
这篇主要分析OceanBase 0.4的mergeserver使用libeasy作为服务器端的模式，客户端自然就是MySQL客户端。OceanBase仅仅使用了libeasy的IO线程部分，工作线程是使用了我们自己的线程池。
主要说如下几个...
dplyr: “Error in n(): function should not be called directly”
...
120
I presume you have dplyr and plyr loaded in the same session. dplyr is not plyr. ddply is not a ...
Show a number to two decimal places
...):
return number_format((float)$number, 2, '.', '');
Example:
$foo = "105";
echo number_format((float)$foo, 2, '.', ''); // Outputs -> 105.00
This function returns a string.
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improv...
Where is the WPF Numeric UpDown control?
...
50
Simply use the IntegerUpDown control in the xtended wpf toolkit
You can use it like this:
Add ...
What is the performance of Objects/Arrays in JavaScript? (specifically for Google V8)
...
+100
I created a test suite, precisely to explore these issues (and more) (archived copy).
And in that sense, you can see the performance...
Transform DateTime into simple Date in Ruby on Rails
....to_date
NoMethodError: undefined method 'to_date' for #<DateTime: -1/2,0,2299161>
from (irb):1
>> require 'active_support/core_ext'
=> true
>> DateTime.new.to_date
=> Mon, 01 Jan -4712
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How can I convert a zero-terminated byte array to string?
I need to read [100]byte to transfer a bunch of string data.
13 Answers
13
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