2019-08-05

创建表练习
////部门表
create table dept(
dept_id int(2) primary key,
dname varchar(20),
addr varchar(20)
);
///员工表
create table emp(
empNO int(4) primary key
ename varchar(10),
job varchar(10),
manager_id varchar(10),
hiredate date,
salary double(7,2),
comm double(7,2),
dept_id int(2)
);
///工资表
create table salary(
s_id int(4) primary key,
s_type int(6),
comm_type int(6)
);
修改员工id字段名
alter table emp change empNO emp_id int(4);
修改属性为非空
alter table emp modify ename varchar(10) not null;