Which would you do:
setter(index, value)
or
setter(value, index)
I would say the first. I normally put the high level argument first, i.e. the index decides where to place the value in.
From a computer's perspective: first you need the location of where to store, when that is found, the value can be set.
It is similar as setting a property of e.g. an element of a car:
SetWheelDiameter(CarModel model, Part.Wheels, Wheel.Diameter, 19.0)
Parameters are from high level to low level.
Googling:
"T value int index"
suggests that it is a lot more common than:
"int index T value"
Related
This question already has answers here:
How to store arrays in MySQL?
(7 answers)
Closed 10 months ago.
I've seen a lot of SQL server script variables of this kind: #variable. But can we, in fact, store an array (associative or not) behind the #variable?
UPDATE
This question turns out to be a duplicate of this one, which suggests to consider possible using of:
SET type and JSON type, which seem to be only column types but not #variable types.
A TEMPORARY TABLE, which seem to be stored in HDD (right?).
Functions working with JSON strings (e.g., JSON_VALUE and JSON_LENGTH), which are usable entirely within MySQL server script. Although, these functions do not help to derive an array and store it in a #variable and are merely JSON walkarounds. I would accept this variant but it seems like #json_string is parsed each time we call JSON_VALUE(#json_string).
So, till now it seems that there IS an opportunity to CREATE an array (associative or not!) but there IS NO an opportunity to surely KEEP the array for its further processing!
Regarding the question mentioned in the beginning of this one. Right now I've only reached 5th and 6th answers, which are related to JSON strings. They are interesting! Be sure to check them out if you're interested in the subject!
Thanks to everyone for your time!
UPDATE
As #Panagiotis Kanavos has mentioned, fetching data by value is slower in case of arrays.
But what if:
We indeed want to simply iterate over M input arrays simultaneously and produce N output arrays? (Maybe, we are simply interested in collation of parameters along a timeline and keep the results.) Arrays are perfectly suitable for this task. But of course, in this case we can still use tables. The question is what will be faster? If our iterative process involves many requests to arrays' elements (can we rely on the server caching the M input arrays and that they'll always be at hand?) and creation of multiple result arrays (how long will it take in case of tables and how do we know that tables are created in RAM for fast access?)?
We want to create an array manually along the course of a server script and are going to only use it in C-like style (aren't going to fetch its data by value) and after the script execution there'll be no need in the array? So, this will be a classic C-like script-only array. To me, in this case putting the array directly into the RAM is what we need and will be more effective than table creation (which'll probably go to HDD), won't it?
And so, the 2nd (and more general) question arises: How far can we rely on the server's optimizations?
I understand that a huge work's been put in optimization in many ways. But has somebody met a situation when a server didn't optimize in the best way? When a programmer had to explicitly rearrange the code in order to manually bring it to the optimal state?
MySQL will implement a data type, ARRAY, to store
variable-sized arrays, in compliance with Standard
SQL (SQL:2003) array functionality.
Syntax
Add a new column data type:
ARRAY [[ may be any data type supported (except
for ARRAY itself, and REF, which MySQL does not support).
It defines the type of data that the array will contain.
-- The [] must be an unsigned integer
greater than zero. It defines the maximum cardinality of
the array, rather than its exact size. Note that the inner
set of brackets is mandatory when defining an array with
a specific size, e.g. INT ARRAY is correct for defining an
array with the default size, INT ARRAY[5] is the correct syntax
for defining an array that will contain 5 elements.
-- As shown in the syntax diagram, []
is optional. If omitted, the maximum cardinality of the
array defaults to an implementation-defined default value.
Oracle's VARRAY size is limited to the maximum number of
columns allowed in a table, so I suggest we make our default
match that maximum. Thus, if [] is omitted,
the maximum cardinality of the array defaults to 1000, which
should also be the absolute maximum cardinality. Thus:
-- [] defaults to 1000.
-- [] may range from 1 to 1000.
Function
An array is an ordered collection of elements, possibly
containing data values. The ARRAY data type will be used
to store data arrays in database tables.
Rules
-- An array is an ordered set of elements.
-- The maximum number of elements in the array is known as
the array's maximum cardinality. The maximum cardinality is
defined at the time the array is defined, as is the element
data type.
-- The actual number of elements that contain data values is
known as the array's cardinality. The cardinality of an array
may vary and is not defined at the time the array is defined.
That is, an instance of an array may always contain fewer
elements than the maximum cardinality allows.
-- Each element may contain a data value that corresponds
to the array's defined data type.
-- Each element has three states: blank (no value assigned
to the element), NULL (NULL assigned to the element), and
containing the valid value (data value assigned to the element).
-- Each element is associated with exactly one ordinal position
in the array. The first array element is found at position 1 (one),
the next at position 2 (two), and so on. Thus, assuming n is the
cardinality of an array, the ordinal position of an array element
is an integer in the range 1 (one) <= element <= n.
-- An array has a maximum cardinality and an actual cardinality.
-- It is an error if one attempts to assign a value to an array
an element whose position is greater than the maximum cardinality of
the array.
-- It is not an error if one attempts to assign values to only
some of an array's elements.
-- Privileges:
-- No special privileges are required to create a table
with the ARRAY data type, or to utilize ARRAY data.
-- Comparison:
-- See WL#2084 Add the ability to compare ARRAY data.
-- Assignment:
-- See WL#2082 Add ARRAY element reference function and
LW #2083 Add ARRAY value constructor function.
Other statements
-- Two other syntax elements must be implemented for
the ARRAY data type to be useful. See WL#2082 for
Array Element Reference syntax and WL#2083 for Array Constructor
syntax.
-- Also related:
-- CARDINALITY(). See WL#2085.
-- Array concatenation. See WL#.
An example
Create a table with the new data type:
CREATE TABLE ArrayTable (array_column INT ARRAY[3]);
Insert data:
INSERT INTO ArrayTable (array_column)
VALUES (ARRAY[10,20,30]);
Retrieve data:
SELECT array_column from ArrayTable
WHERE array_column <> ARRAY[];
-- Returns all cases where array_column is not an empty array
Reserved words
ARRAY, eventually CARDINALITY
Can someone please explain the differences between Null, Zero and Blank in SQL to me?
Zero is a number value. It is a definite with precise mathematical properties. (You can do arithmetic on it ...)
NULL means the absence of any value. You can't do anything with it except test for it.
Blank is ill-defined. It means different things in different contexts to different people. For example:
AFAIK, there is no SQL or MySQL specific technical meaning for "blank". (Try searching the online MySQL manual ...)
For some people "blank" could mean a zero length string value: i.e. one with no characters in it ('').
For some people "blank" could mean a non-zero length string value consisting of only non-printing characters (SPACE, TAB, etc). Or maybe consisting of just a single SPACE character.
In some contexts (where character and string are different types), some people could use "blank" to mean a non-printing character value.
For some people could even use "blank" mean "anything that doesn't show up when you print or display it".
And then there are meanings that are specific to (for example) ORM mappings.
The point is that "blank" does not have a single well-defined meaning. At least not in (native) English IT terminology. It is probably best to avoid it ... if you want other IT professionals to understand what you mean. (And if someone else uses the term and it is not obvious from the context, ask them to say precisely what they mean!)
We cannot say anything generally meaningful about how ZERO / NULL / BLANK are represented, how much memory they occupy or anything like that. All we can say is that they are represented differently to each other .... and that the actual representation is implementation and context dependent.
You may correlate NULL-BLANK-ZERO case by child birth scenario( A real life Example.).
NULL Case: Child is not born yet.
BLANK Case: Child is born but we didn't give any name to him
ZERO Case: We defined it as zero, Child is born but of zero age.
See how this data will look in a database table:
Also NULL is a absence of value, where a field having NULL is not allocated any memory, where as empty fields have empty value with allocated space in memory.
Could you be more accurate about blank?
For what I understand of your question:
"Blank" is the lack of value. This is a human concept. In SQL, you need to fill the field with a value anyway. So that there is a value which means "no value has been set for this field". It is NULL.
If Blank is "", then it is a string, an empty one.
Zero: well, Zero is 0 ... It is a number.
To sum up:
NULL --> no value set
Blank ("") --> empty string
Zero --> Number equal to 0
Please, try to be more accurate next time you post an answer on Stack!
If I were you, I would check some resources about it, for example:
https://www.tutorialspoint.com/sql/sql-null-values.htm
NULL means it does not have any value not even garbage value.
ZERO is an integer value.
BLANK is simply a empty String value.
i couldn't find any specific information in the manual.
can anyone clarify how does ANY , NONE and type unit are reflected in Nim?
short definitions -
a unit type is a type that allows only one value (and thus can hold no information). The carrier (underlying set) associated with a unit type can be any singleton set. There is an isomorphism between any two such sets, so it is customary to talk about the unit type and ignore the details of its value. One may also regard the unit type as the type of 0-tuples, i.e. the product of no types.
ANY -
type ANY also known as ALL or Top , is the universal set. (all possible values).
NONE- the "empty set"
thank you!
Your question seems to be about sets. Let's have a look:
let emptySet: set[int8] = {}
This is an empty set of type int8. The {} literal for the empty set is implicitly casted to any actual set type.
let singletonSet = {1'i8}
This is a set containing exactly one value (a unit type if I understand it correctly). The type of the set can now be automatically deduced from the type of the single value in it.
let completeSet = {low(int8) .. high(int8)}
This set holds all possible int8 values.
The builtin set type is implemented as bitvector and thus can only be used for value types which can hold only a small set of possible values (for int8, the bitvector is already 256 bits long). Besides int8, it is usually used for char and enumeration types.
Then there is HashSet from the module sets which can hold larger types. However, if you construct a HashSet containing all possible values, memory consumption will probably be enormous.
Nim is not a functional language, and never claims to be one. There is no equivalent of these types, and the solution is more like the road that c++ takes.
There is void, wich is closest to what Unit is. The Any type does not exist, but there is the untyped pointer. But that type does not hold any type information in it, so you need to know what you can cast it to. And for NONE, or Nothing how I know it from scala, you have to use void, too. But here you can add the noReturn pragma.
In my template-matching code I need the user to pass a floating-point parameter, which specifies whether the algorithm should concentrate only on the best matches (thus work faster) or analyse even low-probability areas (making it slower).
The parameter is linear and normalized such that possible values are in range <0, 1>. It doesn't matter whether the number of resulting matches increases or decreases as the parameter grows, as this can be easily changed. The default value is around 0.5; when the value is on one end of the range, the algorithm should possibly return only one match (and work fast); whereas the other end should mean lots of possible matches and long processing time.
What name should I choose for this parameter such that it makes sense to the end-user? I've been thinking about MatchingQuality or MatchingDepth but neither seems appropriate and self-explanatory.
I would probably call it matchingAccuracy, matchingPrecision or something like that.
How about MatchThresholdCoefficient?
Can you suggest a precise definition for a 'value' within the context of programming without reference to specific encoding techniques or particular languages or architectures?
[Previous question text, for discussion reference: "What is value in programming? How to define this word precisely?"]
I just happened to be glancing through Pierce's "Types and Programming Languages" - he slips a reasonably precise definition of "value" in a programming context into the text:
[...] defines a subset of terms, called values, that are possible final results of evaluation
This seems like a rather tidy definition - i.e., we take the set of all possible terms, and the ones that can possibly be left over after all evaluation has taken place are values.
Based on the ongoing comments about "bits" being an unacceptable definition, I think this one is a little better (although possibly still flawed):
A value is anything representable on a piece of possibly-infinite Turing machine tape.
Edit: I'm refining this some more.
A value is a member of the set of possible interpretations of any possibly-infinite sequence of symbols.
That is equivalent to the earlier definition based on Turing machine tape, but it actually generalises better.
Here, I'll take a shot: A value is a piece of stored information (in the information-theoretical sense) that can be manipulated by the computer.
(I won't say that a value has meaning; a random number in a register may have no meaning, but it's still a value.)
In short, a value is some assigned meaning to a variable (the object containing the value)
For example type=boolean; name=help; variable=a storage location; value=what is stored in that location;
Further break down:
X = 2; where X is a variable while 2 is the value stored in X.
Have you checked the article in wikipedia?
In computer science, a value is a sequence of bits that is interpreted according to some data type. It is possible for the same sequence of bits to have different values, depending on the type used to interpret its meaning. For instance, the value could be an integer or floating point value, or a string.
Read the Wiki
Value = Value is what we call the "contents" that was stored in the variable
Variables = containers for storing data values
Example: Think of a folder named "Movies"(Variables) and inside of it are it contents which are namely; Pirates of the Carribean, Fantastic Beast, and Lala land, (this in turn is what we now call it's Values )