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Examine the structure of the EMPLOYEES table: EMPLOYEE_ID NUMBER Primary Key FIRST_NAME VARCHAR2(25) LAST_NAME VARCHAR2(25) Which three statements insert a row into the table? （）
A . INSERT INTO employees VALUES ( NULL, 'John', 'Smith');
B . INSERT INTO employees( first_name, last_name) VALUES( 'John', 'Smith');
C . INSERT INTO employees VALUES ( '1000', 'John', NULL);
D . INSERT INTO employees (first_name, last_name, employee_id) VALUES ( 1000, 'John', 'Smith');
E . INSERT INTO employees (employee_id) VALUES (1000);
F . INSERT INTO employees (employee_id, first_name, last_name) VALUES ( 1000, 'John', ' ')
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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)
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Examine the structure of the EMPLOYEES table: EMPLOYEE_ID NUMBER Primary Key FIRST_NAME VARCHAR2(25) LAST_NAME VARCHAR2(25) HIRE_DATE DATE Which UPDATE statement is valid?（）
A . UPDATE employees SET first_name = 'John' SET last_name ='Smith' WHERE employee_id = 180;
B . UPDATE employees SET first_name = 'John', SET last_name ='Smith' WHERE employee_id = 180;
C . UPDATE employees SET first_name = 'John' AND last_name ='Smith' WHERE employee_id = 180;
D . UPDATE employees SET first_name = 'John', last_name ='Smith' WHERE employee_id = 180
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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.
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Examine the structure of the EMPLOYEES table: EMPLOYEE_ID NUMBER Primary Key FIRST_NAME VARCHAR2(25) LAST_NAME VARCHAR2(25) Which three statements inserts a row into the table? （）
A . INSERT INTO employees VALUES (NULL, 'JOHN','Smith');
B . INSERT INTO employees( first_name, last_name) VALUES ('JOHN','Smith');
C . INSERT INTO employees VALUES ('1000','JOHN','NULL');
D . INSERT INTO employees(first_name,last_name, employee_id) VALUES ('1000, 'john','Smith');
E . INSERT INTO employees (employee_id) VALUES (1000);
F . INSERT INTO employees (employee_id, first_name, last_name) VALUES ( 1000, 'john',")
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Examine the structure of the EMPLOYEES table: EMPLOYEE_ID NUMBER Primary Key FIRST_NAME VARCHAR2 (25) LAST_NAME VARCHAR2 (25) HIRE_DATE DATE Which UPDATE statement is valid? （）
A . UPDATE employees SET first_name = 'John' SET last_name = 'Smith' WHERE employee_id = 180;
B . UPDATE employees SET first_name = 'John', SET last_name = 'Smoth' WHERE employee_id = 180;
C . UPDATE employee SET first_name = 'John' AND last_name = 'Smith' WHERE employee_id = 180;
D . UPDATE employee SET first_name = 'John', last_name = 'Smith' WHERE employee_id = 180
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由以下语句创建的表有种子字段，请正确组合插入语句，可不分先后。CREATE TABLE Customer（id int IDENTITY PRIMARY KEY，Customer varchar（40））（）
A . INSERT INTO Customer
B . SET IDENTITY_INSERT Customer ON
C . VALUES（3，’garden shovel’）
D . （id，Customer）
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Examine the structure of the EMPLOYEES table: EMPLOYEE_ID NUMBER Primary Key FIRST_NAME VARCHAR2(25) LAST_NAME VARCHAR2(25) Which three statements insert a row into the table? （）
A . INSERT INTO employees VALUES (NULL, 'John', 'smith');
B . INSERT INTO employees (first_name, last_name) VALUES ('John', 'smith');
C . INSERT INTO employees VALUES ('1000, 'John', 'smith');
D . INSERT INTO employees (first_name, last_name, employee_id) VALUES (1000, 'John', 'smith');
E . INSERT INTO employees (employee_id) VALUES (1000);
F . INSERT INTO employees ( employee_id, first_name, last_name, ) VALUES (1000, 'John','')
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Which of the following will be a consequence of defining the column IDCOL2 in TABLE2 as a foreign key referencing the primary key (IDCOL1) of TABLE1?（）
A . DB2 will no longer allow updating the value of IDCOL1 in TABLE1.
B . When inserting a row in TABLE2, the only values that DB2 will allow for IDCOL2 are the existing values of IDCOL1.
C . When inserting a row in TABLE2, DB2 will only allow foreign values for IDCOL2, that is values which do not exist in IDCOL1.
D . When a SELECT statement joins TABLE1 with TABLE2, DB2 will automatically add the condition TABLE1.IDCOL1=TABLE2.IDCOL2 if not specified in the statement.
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Which two statements are true about the primary key constraint in a table？ （）
A . It is not possible to disable the primary key constraint.
B . It is possible to have more than one primary key constraint in a single table.
C . The primary key constraint can be referred by only one foreign key constraint.
D . The primary key constraint can be imposed by combining more than one column.
E . The non-deferrable primary key constraint creates an unique index on the primary key column if it is not already indexed.
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设有Teachers表，该表的定义如下： CREATE TABLE Teachers（ Tno CHAR（8） PRIMARY KEY， Tname VARCHAR（10） NOT NULL， Age TINYINT CHECK（Age BETWEEN 25 AND 65） ） 下列插入语句中，不能正确执行的是（）。
A . INSERT INTO Teachers VALUES（’T100’，’张宏’，NULL）
B . INSERT INTO Teachers（Tno，Tname，Age） VALUES（’T100’，’张宏’，30）
C . INSERT INTO Teachers（Tno，Tname） VALUES（’T100’，’张宏’）
D . INSERT INTO Teachers VALUES（’T100’，’张宏’）
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CREATE TABLE customer (cid BIGINT NOT NULL PRIMARY KEY, info XML) How many names will be returned for this XQuery?（）https://assets.asklib.com/images/image2/2018080214495585870.jpg
A . 0
B . 1
C . 2
D . 3
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Examine the structure of the EMPLOYEES table: EMPLOYEE_ID NUMBER Primary Key FIRST_NAME VARCHAR2(25) LAST_NAME VARCHAR2(25) HIRE_DATE DATE Which INSERT statement is valid? （）
A . INSERT INTO employees (employee_id, first_name, last_name, hire_date) VALUES (1000, 'John', 'smith','01/01/01);
B . INSERT INTO employees(employee_id, first_name, last_name, hire_date) VALUES (1000, 'John', 'smith','01 january 01');
C . INSERT INTO employees(employee_id, first_name, last_name, Hire_date) VALUES (1000, 'John', 'smith', To_ date ('01/01/01));
D . INSERT INTO employees(employee_id, first_name, last_name, hire_date) VALUES (1000, 'John', 'smith','01-Jan-01')
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Examine the command： ALTER DATABASE ADD SUPPLEMENTAL LOG DATA （PRIMARY KEY） COLUMNS； What does the command accomplish？（）
A . Creates an additional copy of the database online redo log files.
B . Stores the primary key column values of each row involved in a DML operation in the online redo log files.
C . Stores the primary key column values of each row involved in a DML operation in the supplemental log files.
D . Stores the old and new primary key column values of each row involved in a DML operation only when the primary key is modified in the online redo log files.
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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)
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关于主键（primary key）描述正确的是：
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创建“教师表”，其中Tno是主码 , Dno是外码。 CREATE TABLE 教师表 (Tno char(5) CONSTRAINT PK_Tno PRIMARY KEY, Tname char(20) NULL, Dno FOREIGN KEY char(2) REFERENCES 院系表(Dno) )
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The following statements:CREATE TABLE t1 （col1 INT NOT NULL, PRIMARY KEY（col1)); CREATE TA
The following statements:CREATE TABLE t1 (col1 INT NOT NULL, PRIMARY KEY(col1)); CREATE TABLE t2 (col1 INT NOT NULL, col2 CHAR(1) NOT NULL, PRIMARY KEY (col1, col2), FOREIGN KEY (col1) REFERENCES t1 (col1) ON DELETE CASCADE ON UPDATE RESTRICT); CREATE TABLE t3 (col1 INT NOT NULL, col2 INT NOT NULL, PRIMARY KEY (col1, col2),FOREIGN KEY (col1) REFERENCES t1 (col1) ON DELETE NO ACTION ON UPDATE RESTRICT);INSERT INTO t1 VALUES (1), (2); INSERT INTO t2 VALUES (1, ‘a‘), (1, ‘b‘), (2,‘c‘); INSERT INTO t3 VALUES (1, 100), (2, 200), (2,300);How many rows will be deleted by the following DELETE statement？ DELETE FROM t1 WHERE col1= 1;（）
A.4
B.3
C.1
D.0
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For relation where primary key contains multiple attributes, no non-key attribute should be functionally dependent on a part of primary key. This relation R is at least in(66).
A．3NF
B．2NF
C．INF
D．BCNF
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在SQL Server数据库中,UNIQUE约束与PRIMARY KEY约束之间最主要的区别是（）（选一项）
A．UNIQUE约束要求数据库中至少存在一行数据,因此必须在创建数据库表之后才能创建,而PRIMARY KEY约束无此限制
B．UNIQUE约束允许有空值,而PRIMARY KEY约束不允许有空值
C．创建UNIQUE约束后,该数据行允许被更改,而PRIMARY KEY约束的数据行不允许更改
D．UNIQUE约束列不能创建外键,而PRIMARY KEY约束可以创建外键引用
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企业职工和部门的关系模式如下所示，其中部门负责人也是一个职工。职工（职工号，姓名，年龄，月薪，部门号，电话，地址）部门（部门号，部门名，电话，负责人代码，任职时间）请将下面的SQL语句空缺部分补充完整。CREATE TABLE部门（部门号CHAR（4） PRIMARY KEY，部门名CHAR（20），电话CHAR（13），负责人代码CHAR（5），任职时间DATE，FOREIGN KEY（））
A．（电话）REFERENCES（职工电话）
B．（部门号）REFERENCES部门（部门号）
C．（部门号）REFERENCES职工（部门号）
D．（负责人代码）REFERENCES 职工（职工号）
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CREATETABLE命令中的PRIMARY KEY子句用于定于关系的（)。
A．A.实体完整性
B．B.用户定义完整性
C．C.参照完整性
D．D.一致性
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11、若用如下的SQL语句创建了一个表S： CREATE TABLE S （SNO CHAR（6) PRIMARY KEY, NAME CHAR（12) NOT NULL, SEX CHAR（2), AGE INT); 现向S表中插入如下行时，能够成功插入的是（）。
A．('191001', '李明芳', '女', '23')
B．('191002', '张宇', NULL, NULL)
C．(NULL, '陈明', '男', 23)
D．('191003', NULL , '女', '23')
