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Using group by on multiple columns
...te using an example, let's say we have the following table, to do with who is attending what subject at a university:
Table: Subject_Selection
+---------+----------+----------+
| Subject | Semester | Attendee |
+---------+----------+----------+
| ITB001 | 1 | John |
| ITB001 | 1...
Scala: Abstract types vs generics
I was reading A Tour of Scala: Abstract Types . When is it better to use abstract types?
4 Answers
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Why does the JVM still not support tail-call optimization?
...zations , there seems to be a prototype implementation and MLVM has listed the feature as "proto 80%" for some time now.
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I need this baby in a month - send me nine women!
...ss maturity, difficulty of the subject matter, etc.). In order to scope this a bit better so we can speak about it in anything but sweeping oversimplifications, I'm going to restate your question:
Under what circumstances, if any, can adding team members to a software development project that i...
Will iOS launch my app into the background if it was force-quit by the user?
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UPDATE2:
You can achieve this using the new PushKit framework, introduced in iOS 8. Though PushKit is used for VoIP. So your usage should be for VoIP related otherwise there is risk of app rejection. (See this answer).
UDPDATE1:
The documentation h...
What is the Windows equivalent of the diff command?
I know that there is a post similar to this : here .
I tried using the comp command like it mentioned, but if I have two files, one with data like "abcd" and the other with data "abcde", it just says the files are of different sizes. I wanted to know where exactly they differ. In Unix, the simp...
Android Writing Logs to text File
I'm Trying to Write Logs to Custom Log.txt File on Android File using this code of Mine but then this method creates file but contains nothing. Basically I want to read previous contents of the file and then append my data with the existing content.
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Good PHP ORM Library?
Is there a good object-relational-mapping library for PHP?
36 Answers
36
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Convert a series of parent-child relationships into a hierarchical tree?
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This requires a very basic recursive function to parse the child/parent pairs to a tree structure and another recursive function to print it out. Only one function would suffice but here's two for clarity (a combined function c...
Difference between VARCHAR and TEXT in MySQL [duplicate]
... of 65535 characters (you cannot limit the max size)
takes 2 + c bytes of disk space, where c is the length of the stored string.
cannot be (fully) part of an index. One would need to specify a prefix length.
VARCHAR(M)
variable max size of M characters
M needs to be between 1 and 65535
takes 1 ...