A left outer join is a join that returns each element of the first (left) data source, even if it has no correlated elements in the other data source.是什么意思_A left outer join is a join that returns each element of the first (left) data source, even if it has no correlated elements in the other data source.在線(xiàn)翻譯_英語(yǔ)_讀音_用法_例句