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
它运行良好,直到我使它们 LEFT JOIN
s。我认为通过不指定连接类型,它被假定为 LEFT JOIN
。不是这样吗?
最佳答案
I thought that by not specifying a type of join it was assumed to be a LEFT JOIN. Is this not the case?
不,默认联接是 INNER JOIN。
这里是 a visual explanation of SQL joins .
内连接
左加入
关于mysql - MySQL JOIN 与 LEFT JOIN 的区别,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/9770366/