Mysql問題：有沒有像IN ALL查詢？

Question

比如這個查詢：

SELECT `variants`.* 
    FROM `variants` INNER JOIN `variant_attributes` 
    ON variant_attributes.variant_id = variants.id 
WHERE (variant_attributes.id IN ('2','5')) 

和變異的has_many variant_attributes

什麼其實我想要做的就是找到它的變體既有的變體與ID = 2和5屬性，這可能與MySQL？獎金的問題，有沒有一種快速的方式來使用Ruby on Rails，或許可以使用SearchLogic？

解決方案

謝謝Quassnoi爲您提供的查詢，即完美。

要在Rails上使用，我使用了下面的named_scope，我認爲這對初學者來說更容易理解。

基本上named_scope會返回{：from => x，：conditions => y}並且上面的行用於設置y變量。

named_scope :with_variant_attribute_values, lambda { |values| 
    conditions = ["(
      SELECT COUNT(*) 
      FROM `variant_attributes` 
      WHERE variant_attributes.variant_id = variants.id 
        AND variant_attributes.value IN (#{values.collect { |value| "?" }.join ", "}) 
      ) = ? 
    "] 
    conditions = conditions + values + [values.length] 
    { 
    :from => 'variants', 
    :conditions => conditions 
    }} 

Answer 1

Assiuming即variant_attributes (variant_id, id)是獨一無二的：

SELECT `variants`.* 
FROM `variants` 
WHERE (
     SELECT COUNT(*) 
     FROM `variant_attributes` 
     WHERE variant_attributes.variant_id = variants.id 
       AND variant_attributes.id IN ('2','5') 
     ) = 2 

Answer 2

Quassnoi已發佈的MySQL查詢，它，你會喜歡什麼。以下是Variant模型的一種方法，它將起到相當的作用。我做的兩種方法，一是如果variant_attributes (variant_id, id)是一個獨特的組合，以及一個如果他們不

獨特之處：

class Variant < ActiveRecord::Base 
    has_many :variant_attributes 
    named_scope :with_variant_attributes, lamda { |*ids| 
    ids = ids.flatten 
    if(ids.length>0) 
     result = {:include => :variant_attributes} 
     sql_params = {:length => ids.length,:ids => ids} 
     result[:conditions] = ["(:length = (select count(*) from variant_attributes 
              where id in (:ids))",sql_params] 
     result 
    else 
     nil 
    end 
    } 
end 

非唯一

class Variant < ActiveRecord::Base 
    has_many :variant_attributes 
    named_scope :with_variant_attributes, lamda { |*ids| 
    ids = ids.flatten 
    if(ids.length>0) 
     result = {:include => :variant_attributes} 
     conditions = [] 
     sql_params = {} 

     ids.each_with_index do |id,i| 
     conditions << "(1 = Select Count(*) from variant_attributes where id = :id#{i})" 
     sql_params["id#{i}"] = id 
     end 
     result[:conditions] = [ '(' + conditions.join(' AND ') + ')', sql_params] 
     result 
    else 
     nil 
    end 
    } 
end 

可在使用以下方法：

# Returns all Variants with variant_attributes 1, 2, & 3 
vars = Variant.with_variant_attributes(1,2,3) 

# Returns Variant 5 if it has attributes 3 & 5, or null if it doesn't 
vars = Variant.with_variant_attributes(3,5).find_by_id(5) 

#Returns Variants between 1 and 20 if that have an attribute of 2 
vars = Variant.with_variant_attributes(2).find(:conditions => "id between 1 and 20") 

#can accept a variable array of ids 
my_ids = [3,5] 
vars = Variant.with_variant_attributes(my_ids) 

此代碼尚未經過測試。

Answer 3

我會爲此創建named_scope：

class Variant < ActiveRecord::Base 
    has_many :variant_attributes 

    named_scope :with_variant_attributes, lambda { |*ids| { 
      :joins => :variant_attributes, 
      :conditions => {:variant_attributes=>{:id=>ids}}, 
      :group => "variants.id", 
      :having => "count(variants.id) = #{ids.size}" 
      } 
      } 
end 

現在你可以使用指定的範圍如下：

Variant.with_variant_attributes(1,2) 
Variant.with_variant_attributes(1,2,3,4) 

Answer 4

謝謝Quassnoi爲您提供的查詢，即完美。

要在Rails上使用，我使用了下面的named_scope，我認爲這對初學者來說更容易理解。

基本上named_scope會返回{：from => x，：conditions => y}並且上面的行用於設置y變量。

named_scope :with_variant_attribute_values, lambda { |values| 
    conditions = ["(
      SELECT COUNT(*) 
      FROM `variant_attributes` 
      WHERE variant_attributes.variant_id = variants.id 
        AND variant_attributes.value IN (#{values.collect { |value| "?" }.join ", "}) 
      ) = ? 
    "] 
    conditions = conditions + values + [values.length] 
    { 
    :from => 'variants', 
    :conditions => conditions 
    }}