MySQL JOIN与LEFT JOIN的区别 [英] Difference in MySQL JOIN vs LEFT JOIN

问题描述

我有这个跨数据库查询...

I have this cross-database query...

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

在我将它们设置为LEFT JOIN之前运行良好.我认为通过不指定联接类型可以认为它是LEFT JOIN.不是吗?

it runs fine until I make them LEFT JOINs. I thought that by not specifying a type of join it was assumed to be a LEFT JOIN. Is this not the case?

推荐答案

我认为，通过不指定联接类型，可以认为它是LEFT JOIN.不是吗?

I thought that by not specifying a type of join it was assumed to be a LEFT JOIN. Is this not the case?

否，默认联接是INNER JOIN.

No, the default join is an INNER JOIN.

这是对SQL连接.

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