CREATE INDEX BenchmarkId ON exp_weblog_data (field_id_21(6))

SELECT MAX(id) FROM table

<?php
  $random_num = rand(0, $max(id));
?>

SELECT * FROM table WHERE id >= $random_num LIMIT 1

# Change the promote setting of all book nodes that are promoted to the front page.
UPDATE `node` SET `promote` = '0' WHERE `type` = 'book' AND `promote` = '1';

# Promote all book nodes to the front page
UPDATE `node` SET `promote` = '1' WHERE `type` = 'book' AND `promote` = '0';

# Enable commenting for all book pages
UPDATE `node` SET `comment` = '2' WHERE `type` = 'book';

-- mySQL granting DB specific privileges:
GRANT ALL PRIVILEGES on DBNAME.* TO 'user'@'%' IDENTIFIED BY 'password' WITH MAX_QUERIES_PER_HOUR 0 MAX_CONNECTIONS_PER_HOUR 0 MAX_UPDATES_PER_HOUR 0 ;   

-- mySQL granting generic specific privileges:
GRANT ALL PRIVILEGES on *.* TO 'user'@'%' IDENTIFIED BY 'password' WITH MAX_QUERIES_PER_HOUR 0 MAX_CONNECTIONS_PER_HOUR 0 MAX_UPDATES_PER_HOUR 0 ;

zcat <DATABASE>.sql.gz.Z | /Applications/MAMP/Library/bin/mysql --host=localhost --port=8889 --user=root --password=root <DATABASE>

SELECT attributes_ean
FROM products_attributes
WHERE
LENGTH(attributes_ean) = 13
AND
SUBSTRING((10 - ((((
SUBSTRING(attributes_ean FROM 2 FOR 1) +
SUBSTRING(attributes_ean FROM 4 FOR 1) +
SUBSTRING(attributes_ean FROM 6 FOR 1) +
SUBSTRING(attributes_ean FROM 8 FOR 1) +
SUBSTRING(attributes_ean FROM 10 FOR 1) +
SUBSTRING(attributes_ean FROM 12 FOR 1)  
)*3) + (
SUBSTRING(attributes_ean FROM 1 FOR 1) +
SUBSTRING(attributes_ean FROM 3 FOR 1) +
SUBSTRING(attributes_ean FROM 5 FOR 1) +
SUBSTRING(attributes_ean FROM 7 FOR 1) +
SUBSTRING(attributes_ean FROM 9 FOR 1) +
SUBSTRING(attributes_ean FROM 11 FOR 1)
)) MOD 10)) FROM -1 FOR 1) != SUBSTRING(attributes_ean FROM 13 FOR 1)

mysqldump -u<user> -p<password> -hlocalhost <dbname> > nameoffile.sql

mysql -p -h DBSERVER dbname < dbname.sql

#get to the mysql shell and then type "source file.sql",
#where file.sql is your dump file

UPDATE `table` SET `table`.`fieldname` = replace(`fieldname`, 'search_value', 'replace_with') 
WHERE `table`.`firstcondition_field` = 'firstcondition_value'
AND `table`.`secondcondition_field` = 'secondcondition_value'
AND so on...

-- BACKUP, BACKUP, BACKUP!! --

DELETE
FROM child_table
WHERE id
NOT IN
(SELECT id FROM parent_table);