You can import the old
wp_posts table in your current database with different table name,
query and loop through it then update the current
post_content column from the old table where the ID matches.
Here’s an example SQL which you can directly do inside phpMyAdmin (this updates everything in single query)
UPDATE wp_posts SET post_content = ( SELECT post_content FROM temporary_old_wp_posts_backup_table_name WHERE `temporary_old_wp_posts_backup_table_name`.`ID` = `wp_posts`.`ID` LIMIT 1 ) /* just making sure the ID exists on old post table ID*/ WHERE EXISTS( SELECT 1 FROM temporary_old_wp_posts_backup_table_name WHERE `temporary_old_wp_posts_backup_table_name`.`ID` = `wp_posts`.`ID` ) /* probably need a filter to only update post_type = post*/ AND post_type="post"
Another options is to export the
wp_posts from the back-up to a CSV file, loop and read each row and do the same as above (update the post_content of the current post table if ID matches with the id on your csv rows)
Remember to back-up your current database before playing with it. You can also export and import your current database in a new wp install which you can play before running it on live database.