A.ALTER TABLE students ADD PRIMARY KEY student_id;
B.ALTER TABLE students ADD CONSTRAINT PRIMARY KEY (student_id);
C.ALTER TABLE students ADD CONSTRAINT stud_id_pk PRIMARY KEY student_id;
D.ALTER TABLE students ADD CONSTRAINT stud_id_pk PRIMARY KEY (student_id);
E.ALTER TABLE students MODIFY CONSTRAINT stud_id_pk PRIMARY KEY (student_id);

A.A subquery should retrieve only one row.
B.A subquery can retrieve zero or more rows.
C.A subquery can be used only in SQL query statements.
D.Subqueries CANNOT be nested by more than two levels.
E.A subquery CANNOT be used in an SQL query statement that uses group functions.
F.When a subquery is used with an inequality comparison operator in the outer SQL statement, the column list in the SELECT clause of the subquery should contain only one column.

A.UPDATEnew_employeesSETname=（SELECTlast_nameFirst_nameFROMemployeesWHEREemployee_id=180）WHEREemployee_id=180；
B.UPDATEnew_employeesSETname=（SELECTlast_nameFirst_nameFROMemployees）WHEREemployee_id=180；
C.UPDATEnew_employeesSETname=（SELECTlast_nameFirst_nameFROMemployeesWHEREemployee_id=180）   WHEREemployee_id=（SELECTemployee_idFROMnew_employees）；
D.UPDATEnew_employeesSETname=（SELECTlast_nameFirst_nameFROMemployeesWHEREemployee_id=（SELECTemployee_idFROMnew_employees）   WHEREemployee_id=180；

A.USER_CONSTRAINTS
B.USER_OBJECTS
C.ALL_CONSTRAINTS
D.USER_CONS_COLUMNS
E.USER_COLUMNS

A.cannot be nested
B.manipulate data items
C.act on each row returned
D.return one result per row
E.accept only one argument and return only one value
F.accept arguments which can be a column or an expression

A.The value displayed in the CALC_VALUE column will be lower.
B.The value displayed in the CALC_VALUE column will be higher.
C.There will be no difference in the value displayed in the CALC_VALUE column.
D.An error will be reported.

A.CREATE VIEW emp_vu AS SELECT employee_id, emp_name, department_id FROM employees WHERE mgr_id IN (102, 120);
B.CREATE VIEW emp_vu AS SELECT employee_id, emp_name, job_id, department_id FROM employees WHERE mgr_id IN (102, 120);
C.CREATE VIEW emp_vu AS SELECT department_id, SUM(sal) TOTALSAL FROM employees WHERE mgr_id IN (102, 120) GROUP BY department_id;
D.CREATE VIEW emp_vu AS SELECT employee_id, emp_name, job_id, DISTINCT department_id FROM employees;

A.A WHERE clause can be used to restrict both rows and groups.
B.A WHERE clause can be used to restrict rows only.
C.A HAVING clause can be used to restrict both rows and groups.
D.A HAVING clause can be used to restrict groups only.
E.A WHERE clause CANNOT be used in a query if the query uses a HAVING clause.
F.A HAVING clause CANNOT be used in subqueries.

A.The tables being joined have NOT NULL columns.
B.The tables being joined have only matched data.
C.The columns being joined have NULL values.
D.The tables being joined have only unmatched data.
E.The tables being joined have both matched and unmatched data.
F.Only when the tables have a primary key-foreign key relationship.

A.CREATE TABLE orders ( order_id NUMBER(10), customer_id NUMBER(8), order_status NUMBER(10) DEFAULT 'PENDING', date_ordered DATE );
B.CREATE TABLE orders ( order_id NUMBER(10), customer_id NUMBER(8), order_status VARCHAR2(10) = 'PENDING', date_ordered DATE );
C.CREATE OR REPLACE TABLE orders ( order_id NUMBER(10), customer_id NUMBER(8), order_status VARCHAR2(10) DEFAULT 'PENDING', date_ordered DATE );
D.CREATE OR REPLACE TABLE orders ( order_id NUMBER(10), customer_id NUMBER(8), order_status VARCHAR2(10) = 'PENDING', date_ordered DATE );
E.CREATE TABLE orders ( order_id NUMBER(10), customer_id NUMBER(8), order_status VARCHAR2(10) DEFAULT 'PENDING', date_ordered DATE );
F.CREATE TABLE orders ( order_id NUMBER(10), customer_id NUMBER(8), order_status VARCHAR2(10) DEFAULT 'PENDING', date_ordered VARCHAR2 );