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How to store arrays in MySQL?
... will not clutter the row containing the linked item. And the database can index those rows. Arrays typically aren't indexed.
If you don't need relational databases, you can use e.g. a key-value store.
Read about database normalization, please. The golden rule is "[Every] non-key [attribute] must ...
.NET data structures: ArrayList, List, HashTable, Dictionary, SortedList, SortedDictionary — Speed,
...re a fixed size collection that you can change the value stored at a given index.
SortedDictionary is an IDictionary that is sorted based on the keys.
SortedList is an IDictionary that is sorted based on a required IComparer.
So, the IDictionary implementations (those supporting KeyValuePairs) ar...
How to drop columns by name in a data frame
...
You should use either indexing or the subset function. For example :
R> df <- data.frame(x=1:5, y=2:6, z=3:7, u=4:8)
R> df
x y z u
1 1 2 3 4
2 2 3 4 5
3 3 4 5 6
4 4 5 6 7
5 5 6 7 8
Then you can use the which function and the - operat...
Transposing a 2D-array in JavaScript
...
array[0].map((_, colIndex) => array.map(row => row[colIndex]));
map calls a provided callback function once for each element in an array, in order, and constructs a new array from the results. callback is invoked only for indexes of t...
belongs_to through associations
...n. You're better off caching the question_id on Choice and adding a unique index to the table (especially because validates_uniqueness_of is prone to race conditions).
If you're paranoid, add a custom validation to Choice that confirms that the answer's question_id matches, but it sounds like the e...
jar not loaded. See Servlet Spec 2.3, section 9.7.2. Offending class: javax/servlet/Servlet.class
...ommand line useful in tracking down the offending jar file. it creates an index of all the class files in all the jars in the folder. Execute from within the lib folder of your deployed app, then search the index.txt file for the offending class.
for /r %X in (*.jar) do (echo %X & jar -tf %X)...
MySQL: multiple tables or one table with many columns?
...hich can involves seeks on a spinning disk, (2) generally require multiple indexes and some sort of merge, and (3) they make query planning harder, which not only takes time, but also increases the chances that the query optimizer will get something wrong (and badly optimized queries can be really s...
What's the difference between array_merge and array + array?
...rator whereas the all the values will be used with the array_merge, just reindexed.
I generally use union operator for associative arrays and array_merge for numeric. Of course, you can just as well use the array_merge for associative, just that the later values overwrite earlier ones.
...
how to listen to N channels? (dynamic select statement)
...niform pseudo-random choice, and then executes that
case. It returns the index of the chosen case and, if that case was a
receive operation, the value received and a boolean indicating whether
the value corresponds to a send on the channel (as opposed to a zero
value received because the cha...
Absolute vs relative URLs
...scheme#Generic_syntax
foo://username:password@example.com:8042/over/there/index.dtb;type=animal?name=ferret#nose
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