常見(jiàn)例句My finding: Class C was a null set. 我的發(fā)現(xiàn):等級(jí)C是一個(gè)空集。Set Null Sets the value to null if all foreign key columns for the table can accept null values. 設(shè)置空如果表的所有外鍵列都可接受空值,則將該值設(shè)置爲(wèi)空。The null set is any set subset. 空集是指不含任何元素的集郃,空集是任何集郃的子集。Note that this setting is independent of the nulls setting in the columns contained in the foreign key. 注意該設(shè)置與外鍵中所包含列的nulls設(shè)置無(wú)關(guān)。It is now our aim to set up a factory. 我們現(xiàn)在的目的是創(chuàng)辦一座工廠(chǎng)。The state or quality of being null. 無(wú)傚無(wú)傚的狀況或性質(zhì) 返回 null setting