Management of DDL tables and libraries
#1. Create table dept1
NAME NULL? TYPE
id INT(7)
NAME VARCHAR(25)
USE test;
CREATE TABLE dept1(
id INT(7),
NAME VARCHAR(25)
);
#2. Insert the data in the table departments into the new table dept2
CREATE TABLE dept2
SELECT department_id,department_name
FROM myemployees.departments;
#3. Create table emp5
NAME NULL? TYPE
id INT(7)
First_name VARCHAR (25)
Last_name VARCHAR(25)
Dept_id INT(7)
CREATE TABLE emp5(
id INT(7),
first_name VARCHAR(25),
last_name VARCHAR(25),
dept_id INT(7)
);
#4. Increase the length of the column Last_name to 50
ALTER TABLE emp5 MODIFY COLUMN last_name VARCHAR(50);
#5. Create employees2 from table employees
CREATE TABLE employees2 LIKE myemployees.employees;
#6. Drop table emp5
DROP TABLE IF EXISTS emp5;
#7. Rename table employees2 to emp5
ALTER TABLE employees2 RENAME TO emp5;
#8. Add new column test_column in table dept and emp5 and check the operation
ALTER TABLE emp5 ADD COLUMN test_column INT;
#9. Directly delete the column dept_id in the table emp5
DESC emp5;
ALTER TABLE emp5 DROP COLUMN test_column;