For backup and other requirements we often have to copy the data of a table or copy the total table structure with data. We can selectively copy the data of a MySQL table to a new table or copy the total data to a new table. We will learn here different techniques on how to do this.
Read how INSERT ... SELECT with ON DUPLICATE KEY UPDATE is used to export data to an existing table
We can copy a table structure and records to another new table. The CREATE
TABLE command will create a table with same structure of the old table and add
all the records. To export data to an existing table you can use insert command.
CREATE TABLE student2 SELECT * FROM student
This will create a new table student2 using the structure of the table student and will copy all the records from table student to our new table student2.
This became more useful when we add conditions to this by using SQL WHERE
command. This way selectively we can transfer records to a new table. This is
our table.
| id |
name |
class |
mark |
| 1 |
John Deo |
Four |
75 |
| 2 |
Max Ruin |
Three |
85 |
| 3 |
Arnold |
Three |
55 |
| 4 |
Krish Star |
Four |
60 |
| 5 |
John Mike |
Four |
60 |
| 6 |
Alex John |
Four |
55 |
We will apply our sql command to this table to create a new table and we will
copy records for which class = Four. So our new table will contain the
records of class four only.
CREATE TABLE student2 SELECT * FROM student WHERE class='Four'
With this command we will create a new table student2 of same structure of
main table student and all the records of class = Four will be copied to the new
table. The new table student2 will have these records
| id |
name |
class |
mark |
| 1 |
John Deo |
Four |
75 |
| 4 |
Krish Star |
Four |
60 |
| 5 |
John Mike |
Four |
60 |
| 6 |
Alex John |
Four |
55 |
This way we can use any conditional requirements by using where clause to create
or copy different tables.
Copy table structure only
WE can copy only structure and create a new table like this.
create table t1 like student
Here we will create a new table t1 by using structure of student table. ( No data is copied)
Create table if not exists
Note that all the above quires will return error if the table is already exist, so to prevent this error message we can add the command IF NOT EXISTS to the query.
CREATE TABLE IF NOT EXISTS student5 SELECT * FROM student WHERE class='Four'
Here the table will be created only if the table is not there before.
What we will do if we want to delete the old table and create a new table ?
DROP TABLE IF EXISTS
Some time we may not be sure if the table exists or not so we can drop the table if exist by adding one more query before creating the table. Here it is
DROP TABLE IF EXISTS `student5`;
The advantage of the above command over using a simple drop table command is here no error message saying unknown table is generated even if the table is not there.
Copy with extra features like auto_increment
To copy the extra features of the column like auto_increment , unique etc we have to use like this
CREATE TABLE student2 (id INT(3) auto_increment primary key) SELECT student.name,student.class, student.mark from student
Using SHOW CREATE TABLE
We can use query to generate sql dump for creation of a table. The output of above query can be used to create another table.
Here is the query.
SHOW CREATE TABLE student
Script using PHP PDO
Here is a script using php pdo to generate CREATE TABLE query. We assumed that you already have database connection string inside config.php file.
<?Php
require "config.php"; // Database connection string
$table_name='student';
$q = $dbo->prepare("SHOW CREATE TABLE $table_name ");
$q->execute();
$table = $q->fetchAll();
print_r($table);
echo '<br><br>';
echo $table[0]['Create Table'];
?>
The output is here
Array ( [0] => Array ( [Table] => student [0] => student [Create Table] => CREATE TABLE `student` ( `id` int(2) NOT NULL AUTO_INCREMENT, `name` varchar(50) NOT NULL DEFAULT '', `class` varchar(10) NOT NULL DEFAULT '', `mark` int(3) NOT NULL DEFAULT '0', `sex` varchar(6) NOT NULL DEFAULT 'male', UNIQUE KEY `id` (`id`) ) ENGINE=InnoDB AUTO_INCREMENT=36 DEFAULT CHARSET=utf8 [1] => CREATE TABLE `student` ( `id` int(2) NOT NULL AUTO_INCREMENT, `name` varchar(50) NOT NULL DEFAULT '', `class` varchar(10) NOT NULL DEFAULT '', `mark` int(3) NOT NULL DEFAULT '0', `sex` varchar(6) NOT NULL DEFAULT 'male', UNIQUE KEY `id` (`id`) ) ENGINE=InnoDB AUTO_INCREMENT=36 DEFAULT CHARSET=utf8 ) )
CREATE TABLE `student` ( `id` int(2) NOT NULL AUTO_INCREMENT, `name` varchar(50) NOT NULL DEFAULT '', `class` varchar(10) NOT NULL DEFAULT '', `mark` int(3) NOT NULL DEFAULT '0', `sex` varchar(6) NOT NULL DEFAULT 'male', UNIQUE KEY `id` (`id`) ) ENGINE=InnoDB AUTO_INCREMENT=36 DEFAULT CHARSET=utf8
Download sql dump of this student table
More on Alter or coy table , add update or delete records in SQL