In some cases, running an UPDATE statement in production can save the day. However a borked update can be worse than the initial problem.
Short of using a test database, what are options to tell what an update statement will do before running it?
What about Transactions? They have the ROLLBACK-Feature.
@see https://dev.mysql.com/doc/refman/5.0/en/commit.html
For example:
START TRANSACTION;
SELECT * FROM nicetable WHERE somthing=1;
UPDATE nicetable SET nicefield='VALUE' WHERE somthing=1;
SELECT * FROM nicetable WHERE somthing=1; #check
COMMIT;
# or if you want to reset changes
ROLLBACK;
SELECT * FROM nicetable WHERE somthing=1; #should be the old value
In general these lines will not be executed as once. In PHP f.e. you would write something like that (perhaps a little bit cleaner, but wanted to answer quick ;-) ):
$MysqlConnection->query('START TRANSACTION;');
$erg = $MysqlConnection->query('UPDATE MyGuests SET lastname='Doe' WHERE id=2;');
if($erg)
$MysqlConnection->query('COMMIT;');
else
$MysqlConnection->query('ROLLBACK;');
Another way would be to use MySQL Variables (see https://dev.mysql.com/doc/refman/5.7/en/user-variables.html and https://stackoverflow.com/a/18499823/1416909 ):
# do some stuff that should be conditionally rollbacked later on
SET @v1 := UPDATE MyGuests SET lastname='Doe' WHERE id=2;
IF(v1 < 1) THEN
ROLLBACK;
ELSE
COMMIT;
END IF;
But I would suggest to use the language wrappers available in your favorite programming language.