单选题Which statement adds a constraint that ensures the CUSTOMER_NAME column of the CUSTOMERS table holds a value?（）A ALTER TABLE customers ADD CONSTRAINT cust_name_nn CHECK customer_name IS NOT NULL;B ALTER TABLE customers MODIFY CONSTRAINT cust_name_nn CH

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第2题：

要向雇员表中的部门标识列添加FOREIGNKEY约束条件以引用部门表中的标识列，应该使用哪个语句（）

• A、ALTER TABLE雇员MODIFY COLUMN dept_id_fk FOREIGN KEY（部门标识）REFERENCES部门（部门标识）
• B、ALTER TABLE雇员ADD CONSTRAINT dept_id_fk FOREIGNKEY（部门标识）REFERENCES部门（部门标识）
• C、ALTER TABLE雇员ADD FOREIGN KEY CONSTRAINT dept_id_fk ON（部门标识）REFERENCES部门（部门标识）
• D、ALTER TABLE雇员ADD FOREIGN KEY 部门（部门标识）REFERENCES（部门标识）

第3题：

Which syntax turns an existing constraint on?（）

• A、ALTER TABLE table_name   ENABLE constraint_name;
• B、ALTER TABLE table_name   STATUS = ENABLE CONSTRAINT constraint_name;
• C、ALTER TABLE table_name   ENABLE CONSTRAINT constraint_name;
• D、ALTER TABLE table_name   STATUS ENABLE CONSTRAINT constraint_name;
• E、ALTER TABLE table_name   TURN ON CONSTRAINT constraint_name;

第4题：

Which syntax turns an existing constraint on?（）

• A、ALTER TABLE table_name ENABLE constraint_name;
• B、ALTER TABLE table_name STATUS = ENABLE CONSTRAINT constraint _ name;
• C、ALTER TABLE table_name ENABLE CONSTRAINT constraint _ name;
• D、ALTER TABLE table_name TURN ON CONSTRAINT constraint _ name;

第5题：

You need to modify the STUDENTS table to add a primary key on the STUDENT_ID column. The table is currently empty.Which statement accomplishes this task?（）

• 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 MODIFY CONSTRAINT stud _ id _pk PRIMARY KEY (student _ id);

第6题：

Which statement explicitly names a constraint?（）

• A、ALTER TABLE student_grades   ADD   FOREIGN KEY (student_id) REFERENCES students(student_id);
• B、ALTER TABLE student_grades   ADD CONSTRAINT NAME = student_id_fk   FOREIGN KEY (student_id) REFERENCES students(student_id);
• C、ALTER TABLE student_grades   ADD CONSTRAINT student_id_fk   FOREIGN KEY (student_id) REFERENCES students(student_id);
• D、ALTER TABLE student grades   ADD NAMED CONSTRAINT student_id_fk   FOREIGN KEY (student_id) REFERENCES students(student_id);
• E、ALTER TABLE student grades   ADD NAME student_id_fk   FOREIGN KEY (student_id) REFERENCES students(student_id);

第7题：

Examine the following statement that is used to modify the primary key constraint on the SALES table： SQL> ALTER TABLE SALES MODIFY CONSTRAINT pk DISABLE VALIDATE； Which three statements aretrue regarding the above command（）

• A、The constraint remains valid.
• B、The index on the constraint is dropped.
• C、It allows the loading of data into the table using SQL *Loader.
• D、New data conforms to the constraint， but existing data is not checked.
• E、It allows the data manipulation on the table using INSERT/UPDATE/DELETE SQL statements.

第8题：

You need to design the restrictions on the Bank.Customers table. Which three actions should you perform?（）

• A、Design a trigger that verifies that the first names and surnames are not empty strings.
• B、Design a check constraint that verifies that the first names and surnames are not empty strings.
• C、Design a check constraint that uses a CLR user-defined function to verify that either the phone number is a null value or the format of the phone number is valid.
• D、Design a trigger that uses a CLR user-defined function to verify that either the phone number is a null value or the format of the phone number is valid.
• E、Design a check constraint that ensures that the phone number cannot be changed from a valid format to a null value or to an invalid format.
• F、Design a trigger that ensures that the phone number cannot be changed from a valid format to a null value.

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第13题：

为表TEST中ID列添加主键约束的语法是（）

• A、ALTER  TABLE  TEST  CHANGE（ ID  INT  PRIMARY  KEY）
• B、ALTER  TABLE  TEST  ADD（ ID  INT  PRIMARY  KEY）
• C、ALTER  TABLE  TEST  MODIFY（ ID  INT  PRIMARY  KEY）
• D、ALTER  TABLE  TEST  ADD  CONSTRAINT PK  PRIMARY KEY （ID）

第14题：

删除PRIMARYKEY约束条件及其所有依赖约束条件的语法是什么（）

• A、ALTER TABLE table_name DROP CONSTRAINT constraint_name CASCADE
• B、ALTER TABLE table_name DROP CONSTRAINT FOREIGN KEY CASCADE
• C、DROP CONSTRAINT table_name（constraint_name）
• D、ALTER TABLE table_name DROP CONSTRAINT constraint_name

第15题：

What type of constraint is used to ensure that each row inserted into the EMPLOYEE table with a value in the WORKDEPT column has a row with a corresponding value in the DEPTNO column of the DEPARTMENT table?（）

• A、A check constraint on the EMPLOYEE table
• B、A unique constraint on the EMPLOYEE table WORKDEPT column
• C、A foreign key reference from the DEPARTMENT tables DEPTNO column to the WORKDEPT column of the EMPLOYEE table
• D、A foreign key reference from the EMPLOYEE tables WORKDEPT column to the DEPTNO column of the DEPARTMENT table

第16题：

Which statement adds a constraint that ensures the CUSTOMER_NAME column of the CUSTOMERS table holds a value?（）

• A、ALTER TABLE customers ADD CONSTRAINT cust_name_nn CHECK customer_name IS NOT NULL;
• B、ALTER TABLE customers MODIFY CONSTRAINT cust_name_nn CHECK customer_name IS NOT NULL;
• C、ALTER TABLE customers MODIFY customer_name CONSTRAINT cust_name_nn NOT NULL;
• D、ALTER TABLE customers MODIFY customer_name CONSTRAINT cust_name_nn IS NOT NULL;
• E、ALTER TABLE customers MODIFY name CONSTRAINT cust_name_nn NOT NULL;
• F、ALTER TABLE customers ADD CONSTRAINT cust_name_nn CHECK customer_name NOT NULL;

第17题：

You need to modify the STUDENTS table to add a primary key on the STUDENT_ID column. The table is currently empty. Which statement accomplishes this task?（）

• A、ALTER TABLE students ADD PRIMARY KEY _ 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);

第18题：

Examine the following statement that is used to modify the constraint on the SALES table： SQL> ALTER TABLE SALES MODIFY CONSTRAINT pk DISABLE VALIDATE； Which three statements are true regarding the above command（）

• A、The constraint remains valid.
• B、The index on the constraint is dropped.
• C、It allows the loading of data into the table using SQL*Loader.
• D、New data conforms to the constraint， but existing data is not checked
• E、It allows the data manipulation on the table using INSERT/UPDATE/DELETE SQL statements.

第19题：

The EMPLOYEES table has these columns:LAST_NAME VARCHAR2(35) SALARY NUMBER(8,2) HIRE_DATE DATEManagement wants to add a default value to the SALARY column. You plan to alter the table by using this SQL statement:ALTER TABLE EMPLOYEES MODIFY (SALARY DEFAULT 5000);Which is true about your ALTER statement?（）

• A、Column definitions cannot be altered to add DEFAULT values.
• B、A change to the DEFAULT value affects only subsequent insertions to the table.
• C、Column definitions cannot be altered to add DEFAULT values for columns with a NUMBER data type.
• D、All the rows that have a NULL value for the SALARY column will be updated with the value 5000.

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