单项选择题
A SELECT statement can be used to perform these three functions:
1.Choose rows from a table.
2.Choose columns from a table.
3.Bring together data that is stored in different tables by creating a link between them.
Which set of keywords describes these capabilities?（）
A.difference, projection, join
B.selection, projection, join
C.selection, intersection, join
D.intersection, projection, join
E.difference, projection, product
相关考题
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单项选择题
Which SQL statement generates the alias Annual Salary for the calculated column SALARY*12?（）
A.SELECT ename, salary*12 'Annual Salary' FROM employees;
B.SELECT ename, salary*12 "Annual Salary" FROM employees;
C.SELECT ename, salary*12 AS Annual Salary FROM employees;
D.SELECT ename, salary*12 AS INITCAP("ANNUAL SALARY") FROM employees -
多项选择题
What are two reasons to create synonyms? （）
A.You have too many tables.
B.Your tables are too long.
C.Your tables have difficult names.
D.You want to work on your own tables.
E.You want to use another schema's tables.
F.You have too many columns in your tables. -
单项选择题
Click the Exhibit button and examine the data from the ORDERS and CUSTOMERS tables. Which SQL statement retrieves the order ID, customer ID, and order total for the orders that are placed on the same day that Martin placed his orders?（）
A.SELECT ord_id, cust_id, ord_total FROM orders, customers WHERE cust_name='Martin' AND ord_date IN ('18-JUL-2000','21-JUL-2000');
B.SELECT ord_id, cust_id, ord_total FROM orders WHERE ord_date IN (SELECT ord_date FROM orders WHERE cust_id = (SELECT cust_id FROM customers WHERE cust_name = 'Martin'));
C.SELECT ord_id, cust_id, ord_total FROM orders WHERE ord_date IN (SELECT ord_date FROM orders, customers WHERE cust_name = 'Martin');
D.SELECT ord_id, cust_id, ord_total FROM orders WHERE cust_id IN (SELECT cust_id FROM customers WHERE cust_name = 'Martin');
