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Build tree array from flat array in javascript
...n efficient solution if you use a map-lookup. If the parents always come before their children you can merge the two for-loops. It supports multiple roots. It gives an error on dangling branches, but can be modified to ignore them. It doesn't require a 3rd-party library. It's, as far as I can tell, ...
Retrieving the last record in each group - MySQL
... FROM ranked_messages WHERE rn = 1;
Below is the original answer I wrote for this question in 2009:
I write the solution this way:
SELECT m1.*
FROM messages m1 LEFT JOIN messages m2
ON (m1.name = m2.name AND m1.id < m2.id)
WHERE m2.id IS NULL;
Regarding performance, one solution or the o...
What is the most efficient/elegant way to parse a flat table into a tree?
...t can be stored in the same table too. Read "Trees and Hierarchies in SQL for Smarties" by Joe Celko for a lot more information on these designs.
I usually prefer a design called Closure Table (aka "Adjacency Relation") for storing tree-structured data. It requires another table, but then queryin...
How do I find a “gap” in running counter with SQL?
I'd like to find the first "gap" in a counter column in an SQL table. For example, if there are values 1,2,4 and 5 I'd like to find out 3.
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Difference between using bean id and name in Spring configuration file
...r whitespace in the 'name'
attribute.
So basically the id attribute conforms to the XML id attribute standards whereas name is a little more flexible. Generally speaking, I use name pretty much exclusively. It just seems more "Spring-y".
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How to find out client ID of component for ajax update/render? Cannot find component with expression
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Look in HTML output for actual client ID
You need to look in the generated HTML output to find out the right client ID. Open the page in browser, do a rightclick and View Source. Locate the HTML representation of the JSF component of interest a...
Oracle “(+)” Operator
I am checking some old SQL Statements for the purpose of documenting them and probably enhancing them.
4 Answers
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What is the difference between id and class in CSS, and when should I use them? [duplicate]
...ere I gave an id to the div element and it's applying the relevant CSS for it.
15 Answers
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Android: View.setID(int id) programmatically - how to avoid ID conflicts?
I'm adding TextViews programmatically in a for-loop and add them to an ArrayList.
14 Answers
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What are valid values for the id attribute in HTML?
When creating the id attributes for HTML elements, what rules are there for the value?
23 Answers
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