单项选择题

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')) );

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热门试题

单项选择题When defining a referential constraint between the parent table T2 and the dependent table T1, which of the following is true?（）

A.The list of column names in the FOREIGN KEY clause can be a subset of the list of column names in the primary key of T2 or a UNIQUE constraint that exists on T2.
B.The list of column names in the FOREIGN KEY clause can be a subset of the list of column names in the primary key of T1 or a UNIQUE constraint that exists on T1.
C.The list of column names in the FOREIGN KEY clause must be identical to the list of column names in the primary key of T2 or a UNIQUE constraint that exists on T2.
D.The list of column names in the FOREIGN KEY clause must be identical to the list of column names in the primary key of T1 or a UNIQUE constraint that exists on T1.

单项选择题Given the following two tables: TAB1 C1 C2 A 11 B 12 C 13 TAB2 CX CY A 21 C 22 D 23 The following results are desired: C1 C2 CX CY A 11 A 21 C 13 C 22 -- --D 23 Which of the following queries will yield the desired results?（）

A.SELECT * FROM tab1 INNER JOIN tab2 ON c1=cx
B.SELECT * FROM tab1 LEFT OUTER JOIN tab2 ON c1=cx
C.SELECT * FROM tab1 FULL OUTER JOIN tab2 ON c1=cx
D.SELECT * FROM tab1 RIGHT OUTER JOIN tab2 ON c1=cx

单项选择题Given the following two tables: TAB1 R1 A A A B B C C D E TAB2 R2 A A B B C C D Which of the following queries returns the following result set? RETVAL E（）

A.SELECT r1 AS retval FROM tab1 INTERSECT SELECT r2 AS retval FROM tab2
B.SELECT r1 AS retval FROM tab1 EXCEPT SELECT r2 AS retval FROM tab2
C.SELECT DISTINCT r1 AS retval FROM tab1, tab2 WHERE r1 <> r2
D.SELECT r1 AS retval FROM tab1 UNION SELECT r2 AS retval FROM tab2

单项选择题CREATE TABLE customer (cid BIGINT NOT NULL PRIMARY KEY, info XML) How many names will be returned for this XQuery?（）

A.0
B.1
C.2
D.3

单项选择题Which of the following SQL statements will return the year and average salary for all employees hired within a given year that have a salary greater than $30,000?（）

A.SELECT * FROM t1 UNION SELECT * FROM t2
B.SELECT * FROM t1 UNION DISTINCT SELECT * FROM t2
C.SELECT * FROM t1 INTERSECT SELECT * FROM t2
D.SELECT * FROM t1 WHERE (c1,c2)= (SELECT c1,c2 FROM t2)