“雇员”表包含以下列： EMPLOYEE_ID NOT NULL, Primary Key SSNUM NOT NULL

PRIMARY KEY约束和NULL约束不能同时定义在相同的列上。()

若某企业的数据库系统中有如下所示的员工关系和仓库关系，每个仓库可有多名员工，但只有一名负责人。员工关系(cmployee)：

仓库关系(warehouse)：

则创建仓库表结构的SQL语句为(58)。

A．CREATE TABLE(employeeID CHAR(2)NOT NULL UNIQUE, name CHAR(30)NOT NULL, address CHAR(40), pricipallD CHAR(3));

B．CREATE warehouse(warehouseD CHAR(2)PRIMARY KEY, name CHAR(30), address CHAR(40), pficipalID CHAR(3));

C．CREATE TABLE warehouse(warehouselD CHAR(2)PRIMARY KEY, name CHAR(30)NOT NULL, address CHAR(40), pricipalID CHAR(3), FOREIGN KEY(priciPalID)REFERENCES employee(employeeID));

D．CREATE TABLE warehouse(warehouselD CHAR(2), name CHAR(30)NOT NULL, address CHAR(40), pricipalID CHAR(3), PRIMARY KEY(warehouselD), FOREIGN KEY(employeeID)REFERENCES emplo

用SQL语句创建表，使用语句 CREATE TABLE 。对列的约束主要有NOT NULL ，UNIQUE，PRIMARY KEY ，FOREIGN KEY 等。定义表的删除与更新操作的完整性约束，主要有四种模式：NO ACTION ，CASCADE ，SET NULL ，SET DEFAULT 。检查列的取值范围可以用 CHECK 约束。设定列的默认取值，可以用DEFAULT 短语。 ()

设有健身项目表，该表的定义如下：

CREATE TABLE健身项目表（项目编号I PRIMARY KEY，；

项目名称C（30）NOT NULL，；

单价I NULL CHECK（单价>；＝0））

下列插入语句中，提示错误的是（ ）。

A.INSERT INTO健身项目表（项目编号，项目名称，单价）VALUES（1，ˋ瑜伽ˊ，20）

B.INSERT INTO健身项目表（项目编号，项目名称）VALUES（1，ˋ瑜伽ˊ）

C.INSERT INTO健身项目表VALUES（1，ˋ瑜伽ˊ，NULL）

D.INSERT INTO健身项目表（项目名称，单价）VALUES（ˋ瑜伽ˊ，20）

A.0

B.1

C.2

D.3

若用如下的SQL语句创建表S： CREATE TABLES (S# CHAR(6)PRIMARY KEY， SNAME CHAR(8)NOT NULL， SEX CHAR(2)，AGE INTEGER) 并且S表中已经有两行： ('022345'，‘李明芳’，‘女’，23)和('021876'，‘张为’，‘男’，32) 今欲向S表插入新元组：( )。

Ⅰ．('022345’，‘彭鸣明’，‘男’，25)

Ⅱ．('020746'，‘杨云’，NULL，NULL)

Ⅲ．('020721'，‘张为’，‘女’，21)

A．全部

B．Ⅰ和Ⅱ

C．Ⅰ和Ⅲ

D．Ⅱ和Ⅲ

Given the following requirements:Create a table to contain employee data, with a unique numeric identifier automatically assigned when a row is added, has an EDLEVEL column that permits only the values ‘C‘, ‘H‘ and ‘N‘, and permits inserts only when a corresponding value for the employee‘s department exists in the DEPARTMENT table.Which of the following CREATE statements will successfully create this table?（）

A.CREATE TABLE emp ( empno SMALLINT NEXTVAL GENERATED ALWAYS AS IDENTITY, firstname VARCHAR(30) NOT NULL, lastname VARCHAR(30) NOT NULL, workdept CHAR(3) NOT NULL, edlevel CHAR(1), PRIMARY KEY emp_pk (empno), FOREIGN KEY emp_workdept_fk ON (workdept) REFERENCES department (deptno), CHECK edlevel_ck VALUES (edlevel IN (‘C‘,‘H‘,‘N‘)), );

B.CREATE TABLE emp ( empno SMALLINT NOT NULL GENERATED BY DEFAULT AS IDENTITY, firstname VARCHAR(30) NOT NULL, lastname VARCHAR(30) NOT NULL, workdept CHAR(3), edlevel CHAR(1), CONSTRAINT emp_pk PRIMARY KEY (empno), CONSTRAINT emp_workdept_fk FOREIGN KEY (workdept) REFERENCES department (deptno), CONSTRAINT edlevel_ck CHECK edlevel VALUES (‘C‘,‘H‘,‘N‘) );

C.CREATE TABLE emp ( empno SMALLINT NEXTVAL GENERATED BY DEFAULT AS IDENTITY, firstname VARCHAR(30) NOT NULL, lastname VARCHAR(30) NOT NULL, workdept CHAR(3) NOT NULL, edlevel CHAR(1) CHECK IN (‘C‘,‘H‘,‘N‘)), CONSTRAINT emp_pk PRIMARY KEY (empno), CONSTRAINT emp_workdept_fk FOREIGN KEY department (deptno) REFERENCES (workdept) );

D.CREATE TABLE emp ( empno SMALLINT NOT NULL GENERATED BY DEFAULT AS IDENTITY, firstname VARCHAR(30) NOT NULL, lastname VARCHAR(30) NOT NULL, workdept CHAR(3), edlevel CHAR(1), CONSTRAINT emp_pk PRIMARY KEY (empno), CONSTRAINT emp_workdept_fk FOREIGN KEY (workdept) REFERENCES department (deptno), CONSTRAINT edlevel_ck CHECK (edlevel IN (‘C‘,‘H‘,‘N‘)) );

Examine the data in the EMPLOYEES table.On the EMPLOYEES table, EMPLOYEE_ID is the primary key. MGR_ID is the ID of managers and refers to the EMPLOYEE_ID. The JOB_ID column is a NOT NULL column.Evaluate this DELETE statement:Why does the DELETE statement fail when you execute it?（）

A. There is no row with dept_id 90 in the EMPLOYEES table.

B. You cannot delete the JOB_ID column because it is a NOT NULL column.

C. You cannot specify column names in the DELETE clause of the DELETE statement.

D. You cannot delete the EMPLOYEE_ID column because it is the primary key of the table.

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

_____

A．PRIMARY KEY (部门号) NOT NULL UNIQUE

B．PRIMARY KEY (部门名) UNIQUE

C．FOREIGN KEY (负责人) REFERENCES 员工 (姓名)

D．FOREIGN KEY (负责人) REFERENCES 员工 (员工号)

A．

B．

C．

D．