A、CREATE TABLE EMP ( E# CHAR(4) NOT NULL, ENAME CHAR(8) NOT NULL, AGE SMALLINT, SEX CHAR(1), ECITY CHAR(20), PRIMARY KEY(E#)); CREATE TABLE COMP ( C# CHAR(4) NOT NULL, CNAME CHAR(20) NOT NULL, CITY CHAR(20), PRIMARY KEY(C#)); CREATE TABLE WORKS ( E# CHAR(4) NOT NULL, C# CHAR(4) NOT NULL, SALARY SMALLINT, PRIMARY KEY(E#, C#), FOREIGN KEY(E#,C#) REFERENCE EMP(E#),COMP(C#));
B、CREATE TABLE EMP ( E# CHAR(4) NOT NULL, ENAME CHAR(8) NOT NULL, AGE SMALLINT, SEX CHAR(1), ECITY CHAR(20), PRIMARY KEY(E#)); CREATE TABLE COMP ( C# CHAR(4) NOT NULL, CNAME CHAR(20) NOT NULL, CITY CHAR(20), PRIMARY KEY(C#)); CREATE TABLE WORKS ( E# CHAR(4) NOT NULL, C# CHAR(4) NOT NULL, SALARY SMALLINT, PRIMARY KEY(E#, C#), FOREIGN KEY(E#) REFERENCE EMP(E#), FOREIGN KEY(C#) REFERENCES COMP(C#));
C、CREATE TABLE EMP ( E# CHAR(4) NOT NULL, ENAME CHAR(8) NOT NULL, AGE SMALLINT, SEX CHAR(1), ECITY CHAR(20), ); CREATE TABLE COMP ( C# CHAR(4) NOT NULL, CNAME CHAR(20) NOT NULL, CITY CHAR(20), PRIMARY KEY(C#)); CREATE TABLE WORKS ( E# CHAR(4) NOT NULL, C# CHAR(4) NOT NULL, SALARY SMALLINT, PRIMARY KEY(E#, C#), FOREIGN KEY(E#) REFERENCES EMP(E#), FOREIGN KEY(C#) REFERENCES COMP(C#));
D、CREATE TABLE EMP ( E# CHAR(4) NOT NULL, ENAME CHAR(8) NOT NULL, AGE SMALLINT, SEX CHAR(1), ECITY CHAR(20), PRIMARY KEY(E#)); CREATE TABLE COMP ( C# CHAR(4) NOT NULL, CNAME CHAR(20) NOT NULL, CITY CHAR(20), PRIMARY KEY(C#)); CREATE TABLE WORKS ( E# CHAR(4) NOT NULL, C# CHAR(4) NOT NULL, SALARY SMALLINT, PRIMARY KEY(E#, C#), FOREIGN KEY(E#) REFERENCES EMP(E#), FOREIGN KEY(C#) REFERENCES COMP(C#));