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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单选题

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

ALTER TABLE customers ADD CONSTRAINT cust_name_nn CHECK customer_name IS NOT NULL;

ALTER TABLE customers MODIFY CONSTRAINT cust_name_nn CHECK customer_name IS NOT NULL;

ALTER TABLE customers MODIFY customer_name CONSTRAINT cust_name_nn NOT NULL;

ALTER TABLE customers MODIFY customer_name CONSTRAINT cust_name_nn IS NOT NULL;

ALTER TABLE customers MODIFY name CONSTRAINT cust_name_nn NOT NULL;

ALTER TABLE customers ADD CONSTRAINT cust_name_nn CHECK customer_name NOT NULL;

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第1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);

参考答案：C

第2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

参考答案：D

第3题：

在SQL Server 2000中，设有职工表(职工号，职工名，电子邮箱)，现要限制电子邮箱的最后几位的取值为“@abc.com”，且“@”前至少有一位字符。下列添加约束的语句正确的是

A．ALTER TABLE职工表 ADD CONSTRAINT chk_email CHECK(电子邮箱LIKE '_%@abc.com')

B．ALTER TABLE职工表 ADD CONSTRAINT chk_email CHECK(电子邮箱 = '_%@abc.com')

C．ALTER TABLE职工表 ADD CONSTRAINT chk_email CHECK(电子邮箱LIKE '_@abc.com')

D．ALTER TABLE职工表 ADD CONSTRAINT chk_email CHECK(电子邮箱 = '_@abc.com')

正确答案：A

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 STATUS ENABLE CONSTRAINT constraint_name;
E、ALTER TABLE table_name TURN ON CONSTRAINT constraint_name;

正确答案:C

第5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）

正确答案:B

第6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;

参考答案：C

第7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）

正确答案:D

第8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);

参考答案：D

第9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

正确答案:A

第10题：

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

正确答案:D

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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