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从我所了解到的关于左外连接的所有内容中,您希望为空的表应位于等号的右侧。如果是这样的话,为什么这两个查询返回相同的结果:左外连接表排序
SELECT *
FROM employees e
LEFT JOIN cars c ON c.employeeID=e.id AND c.name='Honda City'
WHERE c.id IS NULL
ORDER BY e.id ASC;
SELECT *
FROM employees e
LEFT JOIN cars c ON e.id=c.employeeID AND c.name='Honda City'
WHERE c.id IS NULL
ORDER BY e.id ASC;
演示:http://sqlfiddle.com/#!15/46d00/2
这两个查询是相同的。左侧和右侧来自哪个_table_首先。检查此[小提琴](http://sqlfiddle.com/#!15/46d00/4) – paqogomez