A2-03-13.DDL-How To Rename Table Using MySQL RENAME TABLE Statement
转载自：http://www.mysqltutorial.org/mysql-rename-table/
How To Rename Table Using MySQL RENAME TABLE Statement
Summary: in this tutorial, you will learn how to rename tables using MySQL RENAME TABLE statement and ALTER TABLE statement.
Introduction to MySQL RENAME TABLE statement
Because business requirements change, we need to rename the current table to a new one to better reflect the new situation. MySQL provides us with a very useful statement that changes the name of one or more tables.
To change one or more tables, we use the RENAME TABLE statement as follows:
|
1
|
RENAME TABLE old_table_name TO new_table_name;
|
The old table ( old_table_name) must exist, and the new table ( new_table_name) must not. If the new table new_table_name does exist, the statement will fail.
In addition to the tables, we can use the RENAME TABLE statement to rename views.
Before we execute the RENAME TABLE statement, we must ensure that there is no active transactions or locked tables.
Note that you cannot use the RENAME TABLE statement to rename a temporary table, but you can use the ALTER TABLE statement to rename a temporary table.
In terms of security, any existing privileges that we granted to the old table must be manually migrated to the new table.
Before renaming a table, you should evaluate the impact thoroughly. For example, you should investigate which applications are using the table. If the name of the table changes, so the application code that refers to the table name needs to be changed as well. In addition, you must manually adjust other database objects such as views, stored procedures, triggers, foreign key constraints, etc., that reference to the table. We will discuss this in more detail in the following examples.
MySQL RENAME TABLE examples
First, we create a new database named hr that consists of two tables: employees and departments for the demonstration.
|
1
|
CREATE DATABASE IF NOT EXISTS hr;
|
|
1
2
3
4
5
6
7
8
9
10
11
12
13
|
CREATE TABLE departments (
department_id INT AUTO_INCREMENT PRIMARY KEY,
dept_name VARCHAR(100)
);
CREATE TABLE employees (
id int AUTO_INCREMENT primary key,
first_name varchar(50) not null,
last_name varchar(50) not null,
department_id int not null,
FOREIGN KEY (department_id)
REFERENCES departments (department_id)
);
|
Second, we insert sample data into both employees and departments tables:
|
1
2
|
INSERT INTO departments(dept_name)
VALUES('Sales'),('Markting'),('Finance'),('Accounting'),('Warehouses'),('Production');
|
|
1
2
3
4
5
6
7
|
INSERT INTO employees(first_name,last_name,department_id)
VALUES('John','Doe',1),
('Bush','Lily',2),
('David','Dave',3),
('Mary','Jane',4),
('Jonatha','Josh',5),
('Mateo','More',1);
|
Third, we review our data in the departments and employees tables:
|
1
2
3
4
|
SELECT
department_id, dept_name
FROM
departments;
|
|
1
2
3
4
|
SELECT
id, first_name, last_name, department_id
FROM
employees;
|
Renaming a table referenced by a view
If the table that you are going to rename is referenced by a view, the view will become invalid if you rename the table, and you have to adjust the view manually.
For example, we create a view named v_employee_info based on the employees and departments tables as follows:
|
1
2
3
4
5
6
7
|
CREATE VIEW v_employee_info as
SELECT
id, first_name, last_name, dept_name
from
employees
inner join
departments USING (department_id);
|
The views use the inner join clause to join departments and employees tables.
The following SELECT statement returns all data from the v_employee_info view.
|
1
2
3
4
|
SELECT
*
FROM
v_employee_info;
|
Now we rename the employees to people table and query data from the v_employee_info view again.
|
1
|
RENAME TABLE employees TO people;
|
|
1
2
3
4
|
SELECT
*
FROM
v_employee_info;
|
MySQL returns the following error message:
|
1
2
|
Error Code: 1356. View 'hr.v_employee_info' references invalid table(s) or
column(s) or function(s) or definer/invoker of view lack rights to use them
|
We can use the CHECK TABLE statement to check the status of the v_employee_info view as follows:
|
1
|
CHECK TABLE v_employee_info;
|
We need to manually change the v_employee_info view so that it refers to the people table instead of the employees table.
Renaming a table that referenced by a stored procedure
In case the table that you are going to rename is referenced by a stored procedure, you have to manually adjust it like you did with the view.
First, rename the people table back to the employees table.
|
1
|
RENAME TABLE people TO employees;
|
Then, create a new stored procedure named get_employee that refers to the employees table.
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
|
DELIMITER $$
CREATE PROCEDURE get_employee(IN p_id INT)
BEGIN
SELECT first_name
,last_name
,dept_name
FROM employees
INNER JOIN departments using (department_id)
WHERE id = p_id;
END $$
DELIMITER;
|
Next, we execute the get_employee table to get the data of the employee with id 1 as follows:
|
1
|
CALL get_employee(1);
|
After that, we rename the employees to the people table again.
|
1
|
RENAME TABLE employees TO people;
|
Finally, we call the get_employee stored procedure to get the information of employee with id 2:
|
1
|
CALL get_employee(2);
|
MySQL returns the following error message:
|
1
|
Error Code: 1146. Table 'hr.employees' doesn't exist
|
To fix this, we must manually change the employees table in the stored procedure to people table.
Renaming a table that has foreign keys referenced to
The departments table links to the employees table using the department_id column. The department_id column in the employees table is the foreign key that references to the departments table.
If we rename the departments table, all the foreign keys that point to the departments table will not be automatically updated. In such cases, we must drop and recreate the foreign keys manually.
|
1
|
RENAME TABLE departments TO depts;
|
We delete a department with id 1, because of the foreign key constraint, all rows in the people table should be also deleted. However, we renamed the departments table to the depts table without updating the foreign key manually, MySQL returns an error as illustrated below:
|
1
2
3
|
DELETE FROM depts
WHERE
department_id = 1;
|
|
1
|
Error Code: 1451. Cannot delete or update a parent row: a foreign key constraint fails (`hr`.`people`, CONSTRAINT `people_ibfk_1` FOREIGN KEY (`department_id`) REFERENCES `depts` (`department_id`))
|
Renaming multiple tables
We can also use the RENAME TABLE statement to rename multiple tables at a time. See the following statement:
|
1
2
|
RENAME TABLE old_table_name_1 TO new_table_name_2,
old_table_name_2 TO new_table_name_2,...
|
The following statement renames the people and depts tables to employees and departments tables:
|
1
2
|
RENAME TABLE depts TO departments,
people TO employees;
|
Note the RENAME TABLE statement is not atomic. It means that if any errors occurred, MySQL does a rollback all renamed tables to their old names.
Renaming tables using ALTER TABLE statement
We can rename a table using the ALTER TABLE statement as follows:
|
1
2
|
ALTER TABLE old_table_name
RENAME TO new_table_name;
|
The ALTER TABLE statement can rename a temporary table while the RENAME TABLE statement cannot.
Renaming temporary table example
First, we create a temporary table that contains all unique last names which come from the last_namecolumn of the employees table:
|
1
2
|
CREATE TEMPORARY TABLE lastnames
SELECT DISTINCT last_name from employees;
|
Second, we use the RENAME TABLE to rename the lastnames table:
|
1
|
RENAME TABLE lastnames TO unique_lastnames;
|
MySQL returns the following error message:
|
1
|
Error Code: 1017. Can't find file: '.\hr\lastnames.frm' (errno: 2 - No such file or directory)
|
Third, we use the ALTER TABLE statement to rename the lastnames table.
|
1
2
|
ALTER TABLE lastnames
RENAME TO unique_lastnames;
|
Fourth, we query data from the unique_lastnames temporary table:
|
1
2
3
4
|
SELECT
last_name
FROM
unique_lastnames;
|
In this tutorial, we have shown you how to rename tables using MySQL RENAME TABLE and ALTER TABLE statements.
