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常用Sql - 爬虫/数据库 - 清泛IT社区，为创新赋能！
本帖最后由 zqp2013 于 2015-3-17 22:06 编辑
mysql：drop table if exists tablename;
不能写成
drop table tablename if exists tablename;
mysql：建立索引Sql
CREATE TABLE tablename (
`ID` &nbs...
UnmodifiableMap (Java Collections) vs ImmutableMap (Google) [duplicate]
... still possible:
realMap.put("E", "F");
// The change in the "realMap" is now also visible
// in the "unmodifiableMap". So the unmodifiableMap
// has changed after it has been created.
unmodifiableMap.get("E"); // Will return "F".
In contrast to that, the ImmutableMap of Guava is really immutabl...
Loop backwards using indices in Python?
...
the second argument is one less than the final value. so if you put -1 then the range stops at 0, if you put -5, the range stops at -4 (for an increment of -1)
– mulllhausen
Jul 20 '14 at 14:01
...
How to call a Python function from Node.js
...
Easiest way I know of is to use "child_process" package which comes packaged with node.
Then you can do something like:
const spawn = require("child_process").spawn;
const pythonProcess = spawn('python',["path/to/script.py", arg1, arg2, ....
Selecting a row of pandas series/dataframe by integer index
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What if you wanted the 2nd AND 3rd AND 4th row?
– FaCoffee
Nov 7 '16 at 20:36
1
...
How do I add 1 day to an NSDate?
...= [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
// now build a NSDate object for the next day
NSDateComponents *offsetComponents = [[NSDateComponents alloc] init];
[offsetComponents setDay:1];
NSDate *nextDate = [gregorian dateByAddingComponents:offsetComponents toDate: [N...
What does -> mean in Python function definitions?
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And the information is available as a .__annotations__ attribute.
– Martijn Pieters♦
Jan 17 '13 at 13:06
9
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Remove empty elements from an array in Javascript
... when there were not many useful built-in methods in the Array.prototype.
Now, certainly, I would recommend you to use the filter method.
Take in mind that this method will return you a new array with the elements that pass the criteria of the callback function you provide to it.
For example, if ...
What tools are there for functional programming in C?
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Sadly, this doesn’t work in practice: if you want the closure to capture anything, it requires an executable stack, which is a terrible security practice. Personally, I don’t think it is useful at all.
– Demi
Aug 2 '17 at...
urlencode vs rawurlencode?
If I want to create a URL using a variable I have two choices to encode the string. urlencode() and rawurlencode() .
11 ...