update [table_name] set [field_name] = replace([field_name],'[string_to_find]','[string_to_replace]');
Real World example:
update catalog_product_entity_text set value = replace(value,'®','®');
update [table_name] set [field_name] = replace([field_name],'[string_to_find]','[string_to_replace]');
Real World example:
update catalog_product_entity_text set value = replace(value,'®','®');