您需要从方案中的雇员表中删除EMP_FK_DEPT约束条件。应使用哪条语句（）A、DROP CONSTRAINT EMP_FK_DEPT FROM雇员B、DELETE CONSTRAINT EMP_FK_DEPT FROM雇员C、ALTER TABLE雇员DROP CONSTRAINT EMP_FK_DEPTD、ALTER TABLE雇员REMOVE CONSTRAINT EMP_FK_DEPT
您需要从方案中的雇员表中删除EMP_FK_DEPT约束条件。应使用哪条语句（）
- A、DROP CONSTRAINT EMP_FK_DEPT FROM雇员
- B、DELETE CONSTRAINT EMP_FK_DEPT FROM雇员
- C、ALTER TABLE雇员DROP CONSTRAINT EMP_FK_DEPT
- D、ALTER TABLE雇员REMOVE CONSTRAINT EMP_FK_DEPT
相关考题：
在VisualFoxPro中，如果要将学生表S(学号，姓名，性别，年龄)的“年龄”属性删除，正确的SQL语句是（ ）。A) ALTER TABLE S DROP COLUMN年龄B)DELETE年龄FROM SC)ALTER TABLE S DELETE COLUMN年龄D)ALTER TABLE S DELETE年龄
根据SQL标准，删除表student中对字段sno的唯一性约束，应该使用下面哪条语句? ()A drop sno from table studentB alter table student drop snoC alter table student drop unique(sno)D alter table student drop sno unique
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;
下列哪个SQL语句可以用于从表users中删除数据：（）。A、REMOVE TABLE usersB、DROP TABLE usersC、DELETE FROM usersD、ALTER TABLE users
您需要从您的方案中的“雇员”表中删除“雇员_FK_部门”约束条件。应使用哪条语句？（）A、DROP CONSTRAINT雇员_FK_部门FROM雇员B、DELETE CONSTRAINT雇员_FK_部门FROM雇员C、ALTER TABLE雇员DROP CONSTRAINT雇员_FK_部门D、ALTER TABLE雇员REMOVE CONSTRAINT雇员_FK_部门
应使用哪条语句删除“雇员”表的“姓氏”列上的“姓氏_IDX”索引？（）A、DROP INDEX姓氏_idx；B、DROP INDEX姓氏_idx（姓氏）；C、DROP INDEX姓氏_idx（雇员.姓氏）；D、ALTERTABLE雇员DROP INDEX姓氏_idx；
创建“雇员”表时，可以使用哪个子句来确保薪金值大于或等于1000.00？（）A、CONSTRAINT CHECK 薪金1000B、CHECK CONSTRAINT（薪金1000）C、CONSTRAINT 雇员最低薪金 CHECK薪金1000D、CONSTRAINT 雇员最低薪金 CHECK（薪金=1000）E、CHECK CONSTRAINT 雇员最低薪金（薪金1000）
您在公司的数据库中成功创建了名为SALARY的表。您现在要通过向引用EMPLOYEES表的匹配列的SALARY表添加FOREIGNKEY约束条件来建立EMPLOYEES表与SALARY表之间的父/子关系。尚未向SALARY表添加任何数据。应执行以下哪条语句（）A、ALTER TABLE salary ADD CONSTRAINT fk_employee_id_01 FOREIGN KEY（employee_id）REFERENCES employees（employee_id）B、ALTER TABLE salary ADD CONSTRAINT fk_employee_id_ FOREIGN KEY BETWEEN salary（employee_id）AND employees（employee_id）C、ALTER TABLE salary FOREIGN KEY CONSTRAINT fk_employee_id_REFERENCES employees（employee_id）D、ALTER TABLE salary ADD CONSTRAINT fk_employee_id_FOREIGN KEY salary（employee_id）=employees（employee_id）
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）
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 CASCADEB、ALTER TABLE table_name DROP CONSTRAINT FOREIGN KEY CASCADEC、DROP CONSTRAINT table_name（constraint_name）D、ALTER TABLE table_name DROP CONSTRAINT constraint_name
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;
A constraint in a table is defined with the INITIALLY IMMEDIATE clause. You executed the ALTER TABLEcommand with the ENABLE VALIDATE option to enable the constraint that was disabled. What are the twoeffects of this command（）A、It fails if any existing row violates the constraint.B、It does not validate the existing data in the table.C、It enables the constraint to be enforced at the end of each transaction.D、It prevents insert， update， and delete operations on the table while the constraint is in the process of beingenabled
您的主管让您修改ORDERS表中的AMOUNT列。他要求将该列配置为接受默认值250。该表包含您需要保留的数据。应执行以下哪条语句来完成此任务（）A、ALTER TABLE orders CHANGE DATATYPE amount TO DEFAULT 250B、ALTER TABLE orders MODIFY（amount DEFAULT 250）C、DROP TABLE orders CREATE TABLE orders（orderno varchar2（5）CONSTRAINT pk_orders_01 PRIMARY KEY，customerid varchar2（5）REFERENCES customers（customerid），orderdate date，amount DEFAULT 250）D、DELETE TABLE orders CREATE TABLE orders（orderno varchar2（5）CONSTRAINT pk_orders_01 PRIMARY KEY，customerid varchar2（5）REFERENCES customers（customerid），orderdate date，amount DEFAULT 250）
要删除“雇员标识序列”序列，应使用以下哪条语句（）A、DELETE SEQUENCE雇员标识序列B、DROP SEQUENCE雇员标识序列C、ALTER SEQUENCE雇员标识序列D、REMOV ESEQUENCE雇员标识序列
以下SQL命令执行什么操作（） ALTER TABLE employees ADD CONSTRAINT emp_manager_fk FOREIGN KEY(manager_id) REFERENCES employees(employee_id).A、更改employees表并禁用emp_manager_fk约束条件B、向EMPLOYEES表添加FOREIGN KEY约束条件，要求经理必须已是雇员C、向EMPLOYEES表添加FOREIGN KEY约束条件，要求经理标识应匹配每个雇员标识D、更改employees表并添加FOREIGN KEY约束，要求每个雇员标识必须唯一
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;
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;
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);
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 checkedE、It allows the data manipulation on the table using INSERT/UPDATE/DELETE SQL statements.
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.
单选题您需要从方案中的雇员表中删除EMP_FK_DEPT约束条件。应使用哪条语句（）ADROP CONSTRAINT EMP_FK_DEPT FROM雇员BDELETE CONSTRAINT EMP_FK_DEPT FROM雇员CALTER TABLE雇员DROP CONSTRAINT EMP_FK_DEPTDALTER TABLE雇员REMOVE CONSTRAINT EMP_FK_DEPT
单选题删除PRIMARYKEY约束条件及其所有依赖约束条件的语法是什么（）AALTER TABLE table_name DROP CONSTRAINT constraint_name CASCADEBALTER TABLE table_name DROP CONSTRAINT FOREIGN KEY CASCADECDROP CONSTRAINT table_name（constraint_name）DALTER TABLE table_name DROP CONSTRAINT constraint_name
多选题A constraint in a table is defined with the INITIALLY IMMEDIATE clause. You executed the ALTER TABLEcommand with the ENABLE VALIDATE option to enable the constraint that was disabled. What are the twoeffects of this command（）AIt fails if any existing row violates the constraint.BIt does not validate the existing data in the table.CIt enables the constraint to be enforced at the end of each transaction.DIt prevents insert， update， and delete operations on the table while the constraint is in the process of beingenabled
多选题A constraint in a table is defined with the INITIALLY IMMEDIATE clause. You executed the ALTER TABLE command with the ENABLE VALIDATE option to enable the constraint that was disabled. What are the two effects of this command？（）AIt fails if any existing row violates the constraint.BIt does not validate the existing data in the table.CIt enables the constraint to be enforced at the end of each transaction.DIt prevents insert， update， and delete operations on the table while the constraint is in the process of being enabled.
单选题以下SQL命令执行什么操作（） ALTER TABLE employees ADD CONSTRAINT emp_manager_fk FOREIGN KEY(manager_id) REFERENCES employees(employee_id).A更改employees表并禁用emp_manager_fk约束条件B向EMPLOYEES表添加FOREIGN KEY约束条件，要求经理必须已是雇员C向EMPLOYEES表添加FOREIGN KEY约束条件，要求经理标识应匹配每个雇员标识D更改employees表并添加FOREIGN KEY约束，要求每个雇员标识必须唯一
单选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（）AALTER TABLE雇员MODIFY COLUMN dept_id_fk FOREIGN KEY（部门标识）REFERENCES部门（部门标识）BALTER TABLE雇员ADD CONSTRAINT dept_id_fk FOREIGNKEY（部门标识）REFERENCES部门（部门标识）CALTER TABLE雇员ADD FOREIGN KEY CONSTRAINT dept_id_fk ON（部门标识）REFERENCES部门（部门标识）DALTER TABLE雇员ADD FOREIGN KEY 部门（部门标识）REFERENCES（部门标识）