MySQL JOIN与LEFT JOIN的区别?mysql

我有这个跨数据库查询...

SELECT DM_Server.Jobs.*, DM_Server.servers.Description AS server, digital_inventory.params, products.products_id, products.products_pdfupload, customers.customers_firstname, customers.customers_lastname FROM DM_Server.Jobs INNER JOIN DM_Server.servers ON servers.ServerID = Jobs.Jobs_ServerID JOIN cpod_live.digital_inventory ON digital_inventory.jobname = Jobs.Jobs_Name JOIN cpod_live.products ON products.products_pdfupload = CONCAT(digital_inventory.jobname, ".pdf") JOIN cpod_live.customers ON customers.customers_id = products.cID ORDER BY DM_Server.Jobs.Jobs_StartTime DESC LIMIT 50 运行良好，直到我让他们LEFT JOIN。我认为通过不指定联接类型可以认为是LEFT JOIN。不是吗？