create table EMP(EMPNO NUMBER(4) PRIMARY KEY,ENAME VARCHAR2(10),JOB VARCHAR2(9),MGR NUMBER(4),HIREDATE DATE,SAL NUMBER(7,2),COMM NUMBER(7,2),DEPNO NUMBER(4));CREATE TABLE Dept(DEPTNO NUMBER(4),DNAME VARCHAR2(14),LOC VARCHAR2(13));CREATE TABLE Salgrade(GRADE NUMBER,LOSAL  NUMBER,HISAL NUMBER );CREATE TABLE Bonus(ENAME VARCHAR(10),JOB VARCHAR2(9),SAL NUMBER,COMM NUMBER);INSERT INTO Dept VALUES (10,‘ACCOUNTING‘,‘NEW YORK‘);INSERT INTO Dept VALUES (20,‘RESEARCH‘,‘DALLAS‘);INSERT INTO Dept VALUES (30,‘SALES‘,‘CHICAGO‘);INSERT INTO Dept VALUES (40,‘OPERATIONS‘,‘BOSTON‘);SELECT * FROM DEPT;INSERT INTO EMP VALUES(7369,‘SMITH‘,‘CLERK‘,7902,to_date(‘17-12-1980‘,‘dd-mm-yyyy‘),800,null,20);INSERT INTO EMP VALUES(7499,‘ALLEN‘,‘SALESMAN‘,7698,to_date(‘20-2-1981‘,‘dd-mm-yyyy‘),1600,300,30);INSERT INTO EMP VALUES(7521,‘WARD‘,‘SALESMAN‘,7698,to_date(‘22-2-1981‘,‘dd-mm-yyyy‘),1250,500,30);INSERT INTO EMP VALUES(7566,‘JONES‘,‘MANAGER‘,7839,to_date(‘2-4-1981‘,‘dd-mm-yyyy‘),2975,NULL,20);INSERT INTO EMP VALUES(7654,‘MARTIN‘,‘SALESMAN‘,7698,to_date(‘28-9-1981‘,‘dd-mm-yyyy‘),1250,1400,30);INSERT INTO EMP VALUES(7698,‘BLAKE‘,‘MANAGER‘,7839,to_date(‘1-5-1981‘,‘dd-mm-yyyy‘),2850,NULL,30);INSERT INTO EMP VALUES(7782,‘CLARK‘,‘MANAGER‘,7839,to_date(‘9-6-1981‘,‘dd-mm-yyyy‘),2450,NULL,10);INSERT INTO EMP VALUES(7839,‘KING‘,‘PRESIDENT‘,NULL,to_date(‘17-11-1981‘,‘dd-mm-yyyy‘),5000,NULL,10);INSERT INTO EMP VALUES(7844,‘TURNER‘,‘SALESMAN‘,7698,to_date(‘8-9-1981‘,‘dd-mm-yyyy‘),1500,0,30);INSERT INTO EMP VALUES(7900,‘JAMES‘,‘CLERK‘,7698,to_date(‘3-12-1981‘,‘dd-mm-yyyy‘),950,NULL,30);INSERT INTO EMP VALUES(7902,‘FORD‘,‘ANALYST‘,7566,to_date(‘3-12-1981‘,‘dd-mm-yyyy‘),3000,NULL,20);INSERT INTO EMP VALUES(7934,‘MILLER‘,‘CLERK‘,7782,to_date(‘23-1-1982‘,‘dd-mm-yyyy‘),1300,NULL,10);select * from emp;INSERT INTO SALGRADE VALUES (1,700,1200);INSERT INTO SALGRADE VALUES (2,1201,1400);INSERT INTO SALGRADE VALUES (3,1401,2000);INSERT INTO SALGRADE VALUES (4,2001,3000);INSERT INTO SALGRADE VALUES (5,3001,9999);select * from salgrade;commit; --外键约束CREATE TABLE QQ(    GARDE NUMBER(3) PRIMARY KEY,    GNAME VARCHAR2(20));CREATE TABLE FIREND(    FID NUMBER(3),    NAME VARCHAR2(20),    GRADE NUMBER(3),    FOREIGN KEY(GRADE) REFERENCES QQ(GARDE) ON DELETE CASCADE);    创表时创建外键:  FOREIGN KEY(列名) REFERENCES  引用外键表名(列名) ON DELETE CASCADE创表后添加外键:alter TABLE 表名 ADD constraint   外键约束名 FOREIGN KEY(列名) REFERENCES   引用外键表(列名) ON UPDATE RESTRICT    //同步更新ON DELETE RESTRICT  //  同步删除;.....................................................................................................oracle实现主键id自增 -- 创建表CREATE TABLE t_module (  module_id   INT NOT NULL ,    module_code   varchar(32) NOT NULL,    module_name   varchar(32) NOT NULL,    isnew   INT DEFAULT  0 ,  PRIMARY KEY (module_id))--  为 表 创建 序列-- 从1 开始, 每次 加1CREATE SEQUENCE SEQ_MODULE START WITH 1 INCREMENT BY 1; --查询 下一个 id select seq_module.nextval from dual