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047-174

原创 Linux操作系统 作者:jbymy2000 时间:2012-03-19 10:43:45 0 删除 编辑
174. View the Exhibit and examine the structure of ORDERS and CUSTOMERS
tables.Evaluate the following UPDATE statement:
UPDATE(SELECT order_date, order_total, customer_id
FROM orders)SET order_date = '22mar2007'
WHERE customer_id =(SELECT customer_id
FROM customers WHERE cust_last_name = 'Roberts' AND credit_limit = 600);
Which statement is true regarding the execution of the above UPDATE
statement?
A. It would not execute because two tables cannot be used in a single UPDATE
statement.
B. It would execute and restrict modifications to only the columns specified
in the SELECT statement.
C. It would not execute because a subquery cannot be used in the WHERE clause
of an UPDATE statement.
D. It would not execute because the SELECT statement cannot be used in place
of the table name.
Answer: B

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