What is true about joining tables thro...

单项选择题What is true about joining tables through an equijoin?（）

A. You can join a maximum of two tables through an equijoin.
B. You can join a maximum of two columns through an equijoin.
C. You specify an equijoin condition in the SELECT or FROM clauses of a SELECT statement.
D. To join two tables through an equijoin, the columns in the join condition must be primary key and foreign key columns.
E. You can join n tables (all having single column primary keys) in a SQL statement by specifying a minimum of n-1 join conditions.

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1.多项选择题Which two statements about subqueries are true?（）

A. A single row subquery can retrieve data from only one table.
B. A SQL query statement cannot display data from table B that is referred to in its subquery, unless table B is included in the main query's FROM clause.
C. A SQL query statement can display data from table B that is referred to in its subquery, without including table B in its own FROM clause.
D. A single row subquery can retrieve data from more than one table.
E. A single row subquery cannot be used in a condition where the LIKE operator is used for comparison.
F. A multiple-row subquery cannot be used in a condition where the LIKE operator is used for comparison.

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2.单项选择题You need to calculate the total of all salaries in the accounting department. Which group function should you use?（）

A. MAX
B. MIN
C. SUM
D. COUNT
E. TOTAL
F. LARGEST

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3.单项选择题 Examine the data in the EMPLOYEES and EMP_HIST tables:

The EMP_HIST table is updated at the end of every year. The employee ID, name, job ID, and salary of each existing employee are modified with the latest data. New employee details are added to the table.
Which statement accomplishes this task?（）

A.
B.
C.
D.

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4.单项选择题You define a multiple-row subquery in the WHERE clause of an SQL query with a comparison operator "=".What happens when the main query is executed?（）

A. The main query executes with the first value returned by the subquery.
B. The main query executes with the last value returned by the subquery.
C. The main query executes with all the values returned by the subquery.
D. The main query fails because the multiple-row subquery cannot be used with the comparison operator.
E. You cannot define a multiple-row subquery in the WHERE clause of a SQL query.

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5.多项选择题Which three statements correctly describe the functions and use of constraints? （）

A.Constraints provide data independence.
B.Constraints make complex queries easy.
C.Constraints enforce rules at the view level.
D.Constraints enforce rules at the table level.
E.Constraints prevent the deletion of a table if there are dependencies.
F.Constraints prevent the deletion of an index if there are dependencies.

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6.多项选择题Which two are character manipulation functions? （）

A.TRIM
B.REPLACE
C.TRUNC
D.TO_DATE
E.MOD
F.CASE

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7.单项选择题 Evaluate this SQL statement:
SELECT e.EMPLOYEE_ID,e.LAST_NAME,e.DEPARTMENT_ID, d.DEPARTMENT_NAME FROM EMP e, DEPARTMENT d
WHERE e.DEPARTMENT_ID = d.DEPARTMENT_ID;
In the statement, which capabilities of a SELECT statement are performed?（）

A. Selection, projection, join
B. Difference, projection, join
C. Selection, intersection, join
D. Intersection, projection, join
E. Difference, projection, product

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8.单项选择题You need to perform certain data manipulation operations through a view called EMP_DEPT_VU, which you previously created.You want to look at the definition of the view (the SELECT statement on which the view was create.) How do you obtain the definition of the view?（）

A. Use the DESCRIBE command in the EMP_DEPT VU view.
B. Use the DEFINE VIEW command on the EMP_DEPT VU view.
C. Use the DESCRIBE VIEW command on the EMP_DEPT VU view.
D. Query the USER_VIEWS data dictionary view to search for the EMP_DEPT_VU view.
E. Query the USER_SOURCE data dictionary view to search for the EMP_DEPT_VU view.
F. Query the USER_OBJECTS data dictionary view to search for the EMP_DEPT_VU view.

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9.单项选择题You need to display the last names of those employees who have the letter "A" as the second character in their names.Which SQL statement displays the required results?（）

A. SELECT last_name FROM EMP WHERE last_ name LIKE '_A%';
B. SELECT last_name FROM EMP WHERE last name ='*A%'
C. SELECT last_name FROM EMP WHERE last name ='_A%';
D. SELECT last_name FROM EMP WHERE last name LIKE '*A%'

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10.多项选择题 The ORDERS table has these columns:

The ORDERS table tracks the Order number, the order total, and the customer to whom the Order belongs. Which two statements retrieve orders with an inclusive total that ranges between 100.00 and 2000.00 dollars?（）

A. SELECT customer_id, order_id, order_total   FROM orders   RANGE ON order_total (100 AND 2000) INCLUSIVE;
B. SELECT customer_id, order_id, order_total   FROM orders   HAVING order_total BETWEEN 100 and 2000;
C. SELECT customer_id, order_id, order_total   FROM orders   WHERE order_total BETWEEN 100 and 2000;
D. SELECT customer_id, order_id, order_total   FROM orders   WHERE order_total >= 100 and <= 2000;
E. SELECT customer_id, order_id, order_total   FROM orders   WHERE order_total >= 100 and order_total <= 2000;

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