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What is the difference between t.belongs_to and t.references in rails?
...t words? It seems to me they do the same thing?
Tried some Google search, but find no explanation.
1 Answer
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Finding duplicate values in a SQL table
...ly group on both of the columns.
Note: the older ANSI standard is to have all non-aggregated columns in the GROUP BY but this has changed with the idea of "functional dependency":
In relational database theory, a functional dependency is a constraint between two sets of attributes in a relation...
Scala downwards or decreasing for loop?
In Scala, you often use an iterator to do a for loop in an increasing order like:
7 Answers
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Perform .join on value in array of objects
...Array.prototype.map is what you're looking for if you want to code functionally.
[
{name: "Joe", age: 22},
{name: "Kevin", age: 24},
{name: "Peter", age: 21}
].map(function(elem){
return elem.name;
}).join(",");
In modern JavaScript:
[
{name: "Joe", age: 22},
{name: "Kevin", age: 2...
What are the differences between utf8_general_ci and utf8_unicode_ci? [duplicate]
...tf8_unicode_ci uses the standard Unicode Collation Algorithm, supports so called expansions and ligatures, for example:
German letter ß (U+00DF LETTER SHARP S) is sorted near "ss"
Letter Π(U+0152 LATIN CAPITAL LIGATURE OE) is sorted near "OE".
utf8_general_ci does not support expansions/liga...
java.sql.SQLException: Incorrect string value: '\xF0\x9F\x91\xBD\xF0\x9F…'
...ead:
For a supplementary character, utf8 cannot store the character at all,
while utf8mb4 requires four bytes to store it. Since utf8 cannot store
the character at all, you do not have any supplementary characters in
utf8 columns and you need not worry about converting characters or
losi...
How to change current working directory using a batch file
...st like the commands themselves (CD = cd). I believe that is also true for all external Windows command-line utilities (like FINDSTR, SORT etc.) Third-party tools, on the other hand, can use case-sensitive parameters.
– Andriy M
Feb 28 '17 at 13:36
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Arduino Sketch upload issue - avrdude: stk500_recv(): programmer is not responding
...it works. I figured the packets were some attempt at a hand-shake. So basically, I solved it using Google, patience and futzing around with the board!
– hoipolloi
Jan 12 '14 at 18:16
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What is the difference between join and merge in Pandas?
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pandas.merge() is the underlying function used for all merge/join behavior.
DataFrames provide the pandas.DataFrame.merge() and pandas.DataFrame.join() methods as a convenient way to access the capabilities of pandas.merge(). For example, df1.merge(right=df2, ...) is equiva...
How to create a directory using nerdtree
I have been using NERDTree for a while. Every time I need to create a new directory I need to go to terminal. Is there a quick and easy way to create a directory using NERDTree.
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