Question at position 19 The following code would include: SELECT Customer_T.CustomerID,CustomerName, OrderID FROM Customer_T RIGHT JOIN Order_T ON Customer_T.CustomerID = Order_T.CustomerID;all rows of the Order_T Table regardless of matches with the Customer_T Table.all rows of the Customer_T Table regardless of matches with the Order_T Table.only rows that don't match both Customer_T and Order_T Tables.only rows that match both Customer_T and Order_T Tables.

Question

BlackTom AI · Accepted Answer

We begin by restating the question to focus on the SQL operation: a RIGHT JOIN is performed between Customer_T and Order_T on Customer_T.CustomerID = Order_T.CustomerID, and the question asks which rows this query would include.
Option 1: 'all rows of the Order_T Table regardless of matches with the Customer_T Table.' A RIGHT JOIN returns all rows from the right-hand table (Order_T) and the matching rows from the left-hand table (Customer_T). If there is no match, the left-side columns will be NULL. Therefore, this option correctly describes the effect of a RIGHT JOIN in this context. 
Option 2: 'all rows of the Customer_T Table regardless of matches with the Order_T Table.' This would describe a LEFT JOIN from Customer_T to Order_T, or a RIGHT JOIN with roles reversed, but not a RIGHT JOIN as written, which preserves all rows from the right table (Order_T). Hence this is incorrect for the given query.
Option 3: 'only rows that don’t match both Customer_T and Order_T Tables.' This suggests a full non-matching (anti-join) behavior, which is not what a RIGHT JOIN provides; RIGHT JOIN includes all right rows, including matches, not only non-matching rows. So this is inaccurate for the described query.
Option 4: 'only rows that match both Customer_T and Order_T Tables.' This would be the behavior of an inner join, where only matching pairs appear. Since a RIGHT JOIN includes all right-side rows even when there is no match, this option is not correct for the given statement.
In summary, the critical concept is that a RIGHT JOIN preserves all rows from the right table (Order_T) and brings in matching left-table data when available; non-matching left-side fields appear as NULL. The remaining options mischaracterize which side’s rows are preserved or misinterpret the presence of non-matching rows.

查看解析

登录即可查看完整答案

类似问题

Two tables may be joined:

Question at position 51 We can calculate the cumulative sum for each date using the following SQL statement: SELECT t1.date, t1.precip AS 'daily precip', SUM(t2.precip) AS 'cum. precip' FROM rainfall AS t1 INNER JOIN rainfall AS t2 ON t2.date >= t1.date GROUP BY t1.date ORDER BY t1.date;TrueFalse

Question at position 57 We can calculate the cumulative sum for each date using the following SQL statement: SELECT t1.date, t1.precip AS 'daily precip', SUM(t2.precip) AS 'cum. precip' FROM rainfall AS t1 INNER JOIN rainfall AS t2 ON t2.date >= t1.date GROUP BY t1.date ORDER BY t1.date;TrueFalse

Question at position 57 We can calculate the cumulative sum for each date using the following SQL statement: SELECT t1.date, t1.precip AS 'daily precip', SUM(t2.precip) AS 'cum. precip' FROM rainfall AS t1 INNER JOIN rainfall AS t2 ON t2.date >= t1.date GROUP BY t1.date ORDER BY t1.date;TrueFalse

Question at position 46 Joining conditions for an INNER JOIN always need to use '='.TrueFalse

Question at position 40 One major disadvantage of the outer join is that information is easily lost.TrueFalse

Question at position 17 A join operation:is used to combine indexing operations.causes two tables with a common domain to be combined into a single table or view.causes two disparate tables to be combined into a single table or view.brings together data from two different fields.

更多留学生实用工具

考试浏览器助手

风格化写作助手

论文查重助手

文献引用助手

课堂转译助手

课堂笔记助手

Quiz搜索助手

学校历年真题

智能刷题助手

智能匹配练习

希望你的学习变得更简单