You can write one-line find-and-replace statements in SQL.
To find a string in a certain field and replace it with another string:
UPDATE [table_name] SET [field_name] = REPLACE([field_name],'[string_to_find]','[string_to_replace]');
To not affect date updated for the articles use following sql:
UPDATE [table_name] SET [field_name] = REPLACE([field_name],'[string_to_find]','[string_to_replace]'), date_updated=date_updated;
To find what articles will be affected:
SELECT [field] FROM [table_name] WHERE [field_name] LIKE '%[string_to_find]%';
Example: replace "apple" to "banana" in all articles
UPDATE kbp_kb_entry SET body = REPLACE(body,'apple','banana'), date_updated=date_updated;
