Yes. There must be several, here is one of them:
You can use the function REPLACE (not to be confused with the commando REPLACE) no update. It will return you the complete original string, only with the searched part replaced.
Thus:
UPDATE produtos
SET product_params = REPLACE(product_params, 'max_order_level=""', 'max_order_level="1"')
WHERE product_params LIKE '%max_order_level=""%'
The only restriction would be that the product has this parameter set as you expect (max_order_level=""), only to reduce the amount of records affected to those that will be effectively affected.
See this example working on sql fiddle.
What is the type of column?
– Woss
she is varchar(255)
– Leandro Marzullo
Update product set max_order_level="1"; if you want to do this on all products in the table you do not need Where.
– lpFranz