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How to list all methods for an object in Ruby?
..._of", "execute_simple_calculation", "attr_protected",
"reflections", "table_name_prefix", ...
Note that methods is a method for Classes and for Class instances.
Here's the methods that my User class has that are not in the ActiveRecord base class:
>> User.methods - ActiveRecord::Base...
How can I group by date time column without taking time into consideration
...s fine in oracle
select to_char(columnname, 'DD/MON/yyyy'), count(*) from table_name group by to_char(createddate, 'DD/MON/yyyy');
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Awk学习笔记 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...置函数
控制流命令
4. awk的环境变量
Table 1. awk的环境变量
变量
描述
$n
当前记录的第n个字段，字段间由FS分隔。
$0
完整的输入记录。
ARGC
命令行参数的数目。
...
DateTime2 vs DateTime in SQL Server
...or new
work. These types align with the SQL
Standard. They are more portable.
time, datetime2 and datetimeoffset
provide more seconds precision.
datetimeoffset provides time zone
support for globally deployed
applications.
datetime2 has larger date range, a larger default fractional ...
Find XOR of all numbers in a given range
...f() function calculates the XOR total run from [0, a]. Take a look at this table for 4-bit numbers:
0000 <- 0 [a]
0001 <- 1 [1]
0010 <- 3 [a+1]
0011 <- 0 [0]
0100 <- 4 [a]
0101 <- 1 [1]
0110 <- 7 [a+1]
0111 <- 0 [0]
1000 <- 8 [a]
1001 <- 1 [1]
1010 <- 11 [...
TINYTEXT, TEXT, MEDIUMTEXT, and LONGTEXT maximum storage sizes
...set-unicode-utf8.html, max 3 bytes for utf-8.
THIS IS A ROUGH ESTIMATION TABLE FOR QUICK DECISIONS!
So the worst case assumptions (3 bytes per utf-8 char) to best case (1 byte per utf-8 char)
Assuming the english language has an average of 4.5 letters per word
x is the number of bytes allocated
...
Add UIPickerView & a Button in Action sheet - How?
... to show the action sheet with a modal view controller containing a simple tableview.
There are many ways to accomplish this. Here's one way that I just implemented in a current project. It's nice because I can reuse it between 5 or 6 different screens where I all users to select from a list of op...
How to use greater than operator with date?
...ecords. What I did is to include time, see below example
SELECT * FROM my_table where start_date > '2011-01-01 01:01:01';
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Is it better to return null or empty collection?
...omponent (from a library out of your control), might be rendering an empty table if an empty collection is passed, or no table at all, if null is passed.
in a Object-to-XML (JSON/whatever), where null would mean the element is missing, while an empty collection would render a redundant (and possibly...
Group by with multiple columns using lambda
...
@Jacob - Anonymous types are immutable classes with properly overriden GetHashCode & Equals methods. They where designed for exactly this kind of use case.
– Enigmativity
Aug 4 '11 at 2:57
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