#将departments表中的数据插入到dept2中
CREATE TABLE dept2
SELECT department_id,department_name
FROM myemployees.departments;
#将Last_name的长度修改为50
ALTER TABLE emp5 MODIFY COLUMN Last_name VARCHAR(50);
#根据表employees创建employees2
CREATE TABLE employees2 LIKE myemployees.employees;
CREATE TABLE employees2
SELECT * FROM myemployees.employees;
#删除表emp5
DROP TABLE IF EXISTS emp5;
#将表employees2重命名为emp5
ALTER TABLE employees2 RENAME TO emp5;
#将表dept和emp5中添加新列test_column
ALTER TABLE emp5 ADD COLUMN test_column INT;
ALTER TABLE emp5 ADD COLUMN test_column INT;
#删除表emp5中的列dept_id
ALTER TABLE emp5 DROP COLUMN test_column;