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MySQL - UPDATE multiple rows with different values in one query
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Excuse my english sir, when i try to make an update mysql give me the error: # 1062 - Duplicate entry 'XXX' for key 'PRIMARY'. That does when I try to update a record with the same value it already had, is there any way to skip the update if the current value is the same as be...
Calculate difference between two datetimes in MySQL
I am storing the last login time in MySQL in, datetime -type filed. When users logs in, I want to get the difference between the last login time and the current time (which I get using NOW() ).
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MFC CListCtrl使用方法详解 - C/C++ - 清泛网 - 专注C/C++及内核技术
... Programmatically
http://support.microsoft.com/kb/131284/en-us
19. 如何在CListView中使用CListCtrl的派生类
http://www.codeguru.com/cpp/controls/listview/introduction/article.php/c919/
20. listctrl的subitem添加图标
m_list.SetExtendedStyle(LVS_EX_SUBITEMIMAGES);
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SQL Group By with an Order By
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In all versions of MySQL, simply alias the aggregate in the SELECT list, and order by the alias:
SELECT COUNT(id) AS theCount, `Tag` from `images-tags`
GROUP BY `Tag`
ORDER BY theCount DESC
LIMIT 20
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Difference between scaling horizontally and vertically for databases [closed]
...MongoDB, Google Cloud Spanner .. and a good example of vertical scaling is MySQL - Amazon RDS (The cloud version of MySQL). It provides an easy way to scale vertically by switching from small to bigger machines. This process often involves downtime.
In-Memory Data Grids such as GigaSpaces XAP, Coher...
John Carmack's Unusual Fast Inverse Square Root (Quake III)
... function in the Quake III source code which calculates the inverse square root of a float, 4x faster than regular (float)(1.0/sqrt(x)) , including a strange 0x5f3759df constant. See the code below. Can someone explain line by line what exactly is going on here and why this works so much faster t...
Compare dates in MySQL
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For people comming from google: date type in mysql comes in yyyy-mm-dd format.
– Błażej Michalik
Nov 29 '15 at 20:24
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Count the number of occurrences of a string in a VARCHAR field?
...test 0
test4 valuevaluevaluevaluevalue 5
I don't have MySQL install, but goggled to find the Equivalent of LEN is LENGTH while REPLACE is same.
So the equivalent query in MySql should be
SELECT TITLE,DESCRIPTION, (LENGTH(DESCRIPTION) - LENGTH(REPLACE(DESCRIPTION, 'value', ''))...
Convert text into number in MySQL query
Is it possible to convert text into number within MySQL query? I have a column with an identifier that consists a name and a number in the format of "name-number". The column has VARCHAR type. I want to sort the rows according the number (rows with the same name) but the column is sorted according d...
Mathematical functions in Swift
... sqrt, floor and round because you may natively use respectively 0.5.squareRoot(), Int(0.5) and 0.5.round().
– Cœur
Oct 10 '18 at 10:04
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