liu 發問時間: 社會與文化語言 · 3 年前

[英翻中] 完整的句子在詳細資料中.?

As a more tangible example, consider the expression 22 NOT IN (1, 2, NULL). If you evaluate each individual expression in the parentheses to its truth value, you will get NOT (FALSE OR FALSE OR UNKNOWN), which translates to NOT UNKNOWN, which evaluates to UNKNOWN. The tricky part is that negating UNKNOWN with the NOT operator still yields UNKNOWN; and UNKNOWN is filtered out in a query filter. In short, when you use the NOT IN predicate against a subquery that returns at least one NULL, the outer query always returns an empty set.

3 個解答

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  • 3 年前
    最佳解答

    Sample only:-

    Q{-expression operator--------------------->A:-True value yield;)

    (1)22 not in------------------------------------>(1,2,Null)=F,Not False,Un=not un;

    (2)negate the NOT(not)(refers to (1A)---------------------------->un

    (3)subqueryNOT in(refers to(1Q))---------------------------->un,the predicate=Null

    (4)outerqueryNOT in(refers to (3)-------------------------->un,the empty set.(returns as an empty set).

  • 3 年前

    請問您的疑問是問號嗎?, 那是誤植的. 我是要問詳細資料的句子, 因為我看不懂,

  • 3 年前

    >完整的句子在詳細資料中.?

    你是要問神問題啊?

    是在問什麼啊?

    若是 你只是要翻譯的話,如下:

    As a more tangible example, consider the expression 22 NOT IN (1, 2, NULL).

    當作實用的例子,請考慮這個表敘: 22 NOT IN (1, 2, NULL).

    If you evaluate each individual expression in the parentheses to its truth value, you will get NOT (FALSE OR FALSE OR UNKNOWN), which translates to NOT UNKNOWN, which evaluates to UNKNOWN.

    如果你分析 每一個個別的表述 到它的 個別值,你就會 得到 NOT(FALSE OR FALSE OR UNKNOWN) 而這個值 其實 可以 被分析成 NOT UNKNOWN.

    The tricky part is that negating UNKNOWN with the NOT operator still yields UNKNOWN;

    巧妙的地方是 UNKNOWN 的 反值 還是 UNKNOWN.

    and UNKNOWN is filtered out in a query filter.

    而且 UNKNOWN 在 諮詢 過濾器的過程中 是會被過濾掉的.

    In short, when you use the NOT IN predicate against a subquery that returns at least one NULL, the outer query always returns an empty set.

    簡潔地說,對 次諮詢 的結果 使用 "NOT IN" 敘令 如果 這結果 中包含 最少 一隻 "NULL",那你的 總諮詢結果 一定會 傳回 空集合的.

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