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MongoDB SELECT COUNT GROUP BY
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I need some extra operation based on the result of aggregate function. Finally I've found some solution for aggregate function and the operation based on the result in MongoDB. I've a collection Request with field request, source, status, requestDate.
Single Field Group By & Count:
db.Request...
When should I use nil and NULL in Objective-C?
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technically, they are exactly equal, you can send messages to both nil and to NULL. Idiomatically though nil is usually used to represent an object
– cobbal
Oct 14 '09 at 5:43
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How to remove from a map while iterating it?
...= m.erase(it)" since C++11
}
else
{
++it;
}
}
Note that we really want an ordinary for loop here, since we are modifying the container itself. The range-based loop should be strictly reserved for situations where we only care about the elements. The syntax for the RBFL makes this clear...
How to delete or add column in SQLITE?
...upports a limited subset of ALTER TABLE. The ALTER TABLE command in SQLite allows the user to rename a table or to add a new column to an existing table. It is not possible to rename a column, remove a column, or add or remove constraints from a table.
You can:
create new table as the one you ar...
subtle differences between JavaScript and Lua [closed]
...= operators are of lower precedence than >, >=, <, <=. In Lua, all comparison operators are the same precedence.
Lua supports tail calls.
UPDATE: JS now supports tail calls.
Lua supports assignment to a list of variables. While it isn't yet standard in Javascript, Mozilla's JS engine ...
How can I do a line break (line continuation) in Python?
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Actually, you have the style guide's preference exactly backwards. Implicit continuation is preferred, explicit backslash is to be used only if necessary.
– Carl Meyer
Sep 11 '08 at 19:00
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urlencode vs rawurlencode?
...php.net/manual/en/function.rawurlencode.php)
Returns a string in which all non-alphanumeric characters except -_.~ have been replaced with a percent (%) sign followed by two hex digits. This is the encoding described in » RFC 3986 for protecting literal characters from being interpreted as spec...
How do I provide custom cast support for my class?
...ou want users to have to cast it or whether you want it to happen automagically. Generally, one direction will always work, that's where you use implicit, and the other direction can sometimes fail, that's where you use explicit.
The syntax is like this:
public static implicit operator dbInt64(Byt...
How do I PHP-unserialize a jQuery-serialized form?
.... You do indeed need to parse the string that serialize returns. See the really popular answer below.
– Isaac Lubow
Mar 1 '19 at 2:17
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Finding the index of elements based on a condition using python list comprehension
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In Python, you wouldn't use indexes for this at all, but just deal with the values—[value for value in a if value > 2]. Usually dealing with indexes means you're not doing something the best way.
If you do need an API similar to Matlab's, you would use numpy, a packag...