Magento 1
SET @passwd='newpassord', @salt='5k';
For admin
update admin_user SET password = CONCAT(MD5(CONCAT(@salt , @passwd)), CONCAT(":", @salt )) where email = 'admin@mail.com';
For customer
update customer_entity SET password_hash = CONCAT(MD5(CONCAT(@salt , @passwd)), CONCAT(":", @salt )) where email = 'customer@mail.com';


Magento 2
SET @passwd='newpassord', @salt=MD5(RAND());
For admin
update admin_user SET password = CONCAT(SHA2(CONCAT(@salt, @passwd), 256), ':', @salt, ':1') where email = 'admin@mail.com';
For customer
update customer_entity SET password_hash = CONCAT(SHA2(CONCAT(@salt, @passwd), 256), ':', @salt, ':1') where email = 'customer@mail.com';