create table depm ( depm_id number(3) constraint dep_id_pk primary key, depm_name varchar(30) not null)
create table emp2( emp2_id number(4) constraint emp2_id_pk primary key, emp2_name varchar(20) not null, email varchar(40) not null, constraint emp2_email_uk unique(email), depm_id number(3) , constraint fk_emp2_depm foreign key(depm_id) references depm(depm_id))
1、创建表CREATE TABLE students (student_id VARCHAR2(10) NOT NULL, student_name VARCHAR2(30) NOT NULL, college_major VARCHAR2(15) NOT NULL, status VARCHAR2(20) NOT NULL, state VARCHAR2(2), license_no VARCHAR2(30)) TABLESPACE student_data;2、创建主键ALTER TABLE students ADD CONSTRAINT pk_students PRIMARY KEY (student_id) USING INDEX TABLESPACE student_index;3、创建Unique约束ALTER TABLE students ADD CONSTRAINT uk_students_license UNIQUE (state, license_no) USING INDEX TABLESPACE student_index;4、创建Check约束ALTER TABLE students ADD CONSTRAINT ck_students_st_lic CHECK ((state IS NULL AND license_no IS NULL) OR (state IS NOT NULL AND license_no is NOT NULL));5、创建外键约束ALTER TABLE students ADD CONSTRAINT fk_students_state FOREIGN KEY (state) REFERENCES state_lookup (state);
