address VARCHAR(50),
country VARCHAR(50) NOT NULL,
postalCode VARCHAR(15) UNIQUE,
PRIMARY KEY(officeCode)
);
CREATE TABLE employees(
employeeNumber INT(11) PRIMARY KEY AUTO_INCREMENT,
lastName VARCHAR(50) NOT NULL,
firstName VARCHAR(50) NOT NULL,
mobile VARCHAR(25) UNIQUE,
officeCode INT(10) NOT NULL,
jobTitle VARCHAR(50) NOT NULL,
birth DATETIME NOT NULL,
note VARCHAR(255),
sex VARCHAR(5),
CONSTRAINT fk_emp_ofCode FOREIGN KEY(officeCode) REFERENCES offices(officeCode)
);
#3. 将表employees的mobile字段修改到officeCode字段后面
ALTER TABLE employees MODIFY mobile VARCHAR(25) AFTER officeCode;
#4. 将表employees的birth字段改名为employee_birth
ALTER TABLE employees CHANGE birth employee_birth DATETIME;
#5. 修改sex字段,数据类型为CHAR(1),非空约束
ALTER TABLE employees MODIFY sex CHAR(1) NOT NULL;
#6. 删除字段note
ALTER TABLE employees DROP COLUMN note;
#7. 增加字段名favoriate_activity,数据类型为VARCHAR(100)
ALTER TABLE employees ADD favoriate_activity VARCHAR(100);
#8. 将表employees名称修改为employees_info
ALTER TABLE employees RENAME employees_info;