set-difference | 易学教程

Trying to understand “except all” in sql query

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问题 I came across this example and I don't understand what it means. (SELECT drinker FROM Frequents) EXCEPT ALL (SELECT drinker FROM Likes); relations: Frequents(drinker, bar), Likes(drinker, beer) What does the ALL do in this case? How is the result different from the query below? (SELECT drinker FROM Frequents) EXCEPT (SELECT drinker FROM Likes); 回答1: The SQL EXCEPT operator takes the distinct rows of one query and returns the rows that do not appear in a second result set. The EXCEPT ALL

How to calculate difference between two sets in emacs lisp,the sets should be lists

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问题 How to calculate the difference between two sets in Emacs Lisp? The sets should be lists. The programm should be very simple and short, or else I won't understand it. I'm a newbee. Thx 回答1: There is a set-difference function in the Common Lisp extensions: elisp> (require 'cl) cl elisp> (set-difference '(1 2 3) '(2 3 4)) (1) 回答2: When I write Elisp code that has lots of list data transformations, I use dash library, because it has loads of functions to work with lists. Set difference can be

Can the following Nested foreach loop be simplified in PowerShell?

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问题 I have created a script that loops through an array and excludes any variables that are found within a second array. While the code works; it got me wondering if it could be simplified or piped. $result = @() $ItemArray = @("a","b","c","d") $exclusionArray = @("b","c") foreach ($Item in $ItemArray) { $matchFailover = $false :gohere foreach ($ExclusionItem in $exclusionArray) { if ($Item -eq $ExclusionItem) { Write-Host "Match: $Item = $ExclusionItem" $matchFailover = $true break :gohere }

Not in In SQL statement?

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问题 I have set of ids in excel around 5000 and in the table I have ids around 30000. If I use 'In' condition in SQL statment I am getting around 4300 ids from what ever I have ids in Excel. But If I use 'Not In' with Excel id. I have getting around 25000+ records. I just to find out I am missing with Excel ids in the table. How to write sql for this? Example: Excel Ids are 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, Table has IDs 1, 2, 3, 4, 6, 8, 9, 11, 12, 14, 15 Now I want get 5,7,10 values from Excel

Not in In SQL statement?

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I have set of ids in excel around 5000 and in the table I have ids around 30000. If I use 'In' condition in SQL statment I am getting around 4300 ids from what ever I have ids in Excel. But If I use 'Not In' with Excel id. I have getting around 25000+ records. I just to find out I am missing with Excel ids in the table. How to write sql for this? Example: Excel Ids are 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, Table has IDs 1, 2, 3, 4, 6, 8, 9, 11, 12, 14, 15 Now I want get 5,7,10 values from Excel which missing the table? Update: What I am doing is SELECT [GLID] FROM [tbl_Detail] where datasource =

Trying to understand “except all” in sql query

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I came across this example and I don't understand what it means. (SELECT drinker FROM Frequents) EXCEPT ALL (SELECT drinker FROM Likes); relations: Frequents(drinker, bar), Likes(drinker, beer) What does the ALL do in this case? How is the result different from the query below? (SELECT drinker FROM Frequents) EXCEPT (SELECT drinker FROM Likes); The SQL EXCEPT operator takes the distinct rows of one query and returns the rows that do not appear in a second result set. The EXCEPT ALL operator does not remove duplicates. For purposes of row elimination and duplicate removal, the EXCEPT operator

All-to-all setdiff on two numeric vectors with a numeric threshold for accepting matches

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问题 What I want to do is more or less a combination of the problems discussed in the two following threads: Perform non-pairwise all-to-all comparisons between two unordered character vectors --- The opposite of intersect --- all-to-all setdiff Merge data frames based on numeric rownames within a chosen threshold and keeping unmatched rows as well I have two numeric vectors: b_1 <- c(543.4591, 489.36325, 12.03, 896.158, 1002.5698, 301.569) b_2 <- c(22.12, 53, 12.02, 543.4891, 5666.31, 100.1, 896

How to do sane “set-difference” in Ruby?

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问题 Demo (I expect result [3] ): [1,2] - [1,2,3] => [] # Hmm [1,2,3] - [1,2] => [3] # I see a = [1,2].to_set => #<Set: {1, 2}> b = [1,2,3].to_set => #<Set: {1, 2, 3}> a - b => #<Set: {}> WTF! And: [1,2,9] - [1,2,3] => [9] # Hmm. Would like [[9],[3]] How is one to perform a real set difference regardless of order of the inputs? Ps. As an aside, I need to do this for two 2000-element arrays. Usually, array #1 will have fewer elements than array #2, but this is not guaranteed. 回答1: The - operator

Error while doing set_difference: Variable result is not a structure

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问题 i had declared a set variable outside a function globally. std::set<std::string> s1; std::set<std::string> s2; std::set<std::string> intersect; std::set<std::string> _result_; //here is the declaration Now i try to populate that structure inside a function. s1.insert("1-1"); s2.insert("1-1"); std::set_intersection( s1.begin(), s1.end(), s2.begin(), s2.end(),std::insert_iterator< std::set<std::string> >( intersect, intersect.begin() ) ); std::set_difference(s1.begin(), s1.end(), s2.begin(), s2

How to do sane “set-difference” in Ruby?

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Demo (I expect result [3] ): [1,2] - [1,2,3] => [] # Hmm [1,2,3] - [1,2] => [3] # I see a = [1,2].to_set => #<Set: {1, 2}> b = [1,2,3].to_set => #<Set: {1, 2, 3}> a - b => #<Set: {}> WTF! And: [1,2,9] - [1,2,3] => [9] # Hmm. Would like [[9],[3]] How is one to perform a real set difference regardless of order of the inputs? Ps. As an aside, I need to do this for two 2000-element arrays. Usually, array #1 will have fewer elements than array #2, but this is not guaranteed. The - operator applied to two arrays a and b gives the relative complement of b in a (items that are in a but not in b ).