clsql:为什么要“神奇地”添加表？

Question

假设我有以下两个表

(clsql:def-view-class class-a ()
  ((field-one :type integer
              :db-kind :key
              :db-constraints :auto-increment)
   (field-two :type string
              :initarg :two
              :db-constraints :not-null)))

(clsql:def-view-class class-b ()
  ((b-one :type integer
          :initarg :b-one
          :db-kind :key)))

(clsql:create-view-from-class 'class-a)
(clsql:create-view-from-class 'class-b)

现在我需要a类的条目，这些条目在b类中没有对应的条目。(“对应”表示class-a.field-one映射到class-b.b-one。)假设a类有以下两个条目：

(clsql:update-records-from-instance (make-instance 'class-a :two "hello"))
(clsql:update-records-from-instance (make-instance 'class-a :two "world"))

因此，要发出的查询将是：

(clsql:select 'class-a :from [class-a] ; class-b is added "magically"
              :where [not [in [class-a field-one]
                              [select [class-b b-one] :from [class-b]
                                      :where [= [class-a field-one]
                                                [class-b b-one]]]]])

然而，这也增加了class-b。(有了一个故意的错误，我得到的查询执行如下：)

SELECT CLASS_A.FIELD_ONE,CLASS_A.FIELD_TWO FROM CLASS_A,CLASS_B 
  WHERE (NOT ((CLASS_A.FIELD_ONE 
                IN (SELECT CLASS_B.B_ONE FROM CLASS_B 
                      WHERE (CLASS_A.FIELD_ONE = CLASS_B.B_ONE)))))

另一方面，

(clsql:select [*] :from [class-a] ; see the [*]
              :where [not [in [class-a field-one]
                              [select [class-b b-one] :from [class-b]
                                      :where [= [class-a field-one]
                                                [class-b b-one]]]]])

被翻译成预期的：

SELECT * FROM CLASS_A 
  WHERE (NOT ((CLASS_A.FIELD_ONE 
                IN (SELECT CLASS_B.B_ONE FROM CLASS_B 
                      WHERE (CLASS_A.FIELD_ONE = CLASS_B.B_ONE)))))

这是一个bug，还是这个翻译背后有什么原因？

Answer 1

从版本6.7.0开始，重新定义函数clsql-sys::%tables-for-query使其“按预期”工作，而不会破坏我正在处理的webapp应用程序中的任何内容：

(in-package :clsql-sys)

(defun %tables-for-query (classes from where inner-joins)
  (declare (ignore where inner-joins))
  (union (mapcar #'select-table-sql-expr classes)
         (listify from)))

但是我还没有运行测试用例clsql-tests。