It is possible to Simulate a MySQL query before running it with the use of  MySQL-Transactions and the build in ROLLBACK-Feature of MySQL:

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

For further information see https://dev.mysql.com/doc/refman/5.0/en/commit.html and my answer on stackoverflow.com.