Reset a table using query in sql - php

Question

can here is any reset query which reset the table after update.
I update a colum and then I want to reset it.
id name
1 azeem
2 arfan
update the table.
update table set name = 'abc' where id = 1;
update table set name = 'xyz' where id = 2;
id name
1 abc
2 xyz
Update:
$sql = mysql_query("select * from table");
while($row = mysql_fetch_array($sql)){
echo $row['name'];
}
After that I want to reset it. How can I do that.?

Answer 1

2 Ways.
If you're running a test server and want to restore back all of the info that you're changing, then you can make a backup and restore the table values after the update.
otherwise if you're talking about at the transaction level you can make a transaction and instead of committing, roll it back.
<?php
/* Begin a transaction, turning off autocommit */
$dbh->beginTransaction();
/* Change the database schema and data */
$sth = $dbh->exec("DROP TABLE fruit");
$sth = $dbh->exec("UPDATE dessert
SET name = 'hamburger'");
/* Recognize mistake and roll back changes */
$dbh->rollBack();
/* Database connection is now back in autocommit mode */
?>

Answer 2

Yes you can, as sgeddes said, you need to use a transaction. When you use a transaction which is not committed you can rollback to the state before the query executed.
Try this:
//Start the transaction
mysql_query("START TRANSACTION");
//An update query
$yourUpdateQuery = mysql_query("UPDATE YOUR_TBL SET COLUMN = 'COLUMN_VALUE' WHERE COLUMN_ID = ID_VALUE");
//Some SQL select queries (note, that this do not have effect on your data, so this don't need to be in your transaction
$sql = mysql_query("select * from table");
while($row = mysql_fetch_array($sql))
{
echo $row['name'];
}
//Some check here
if (1==1) {
//Ok, let's finish it
mysql_query("COMMIT");
} else {
//Not ok, rollback to the state before the transaction started.
mysql_query("ROLLBACK");
}
Note that you and the above example are using mysql_* functions which are deprecated. You should use PDO instead of mysql_*.
Here is a PDO example:
<?php
//PDO Database connection (if you haven't done this)
$db = new PDO('mysql:host=localhost;dbname=DATABASE_NAME', "USERNAME", "PASSWORD");
//Start the transaction
$db->beginTransaction();
//An update query
$db = $db->exec("UPDATE YOUR_TBL SET COLUMN = 'COLUMN_VALUE' WHERE COLUMN_ID = ID_VALUE");
//Some SQL select queries (note, that this do not have effect on your data, so this don't need to be in your transaction
$sql = 'select * from table';
foreach($db->query($sql) as $row)
{
echo $row['name'];
}
//Some check here
if (1==1) {
//Ok, let's finish it
$db->commit();
} else {
//Not ok, rollback to the state before the transaction started.
$db->rollBack();
}
?>