例如,
SELECT p1.country_code, p1.size AS size2010, p2.size AS size2015 FROM populations AS p1 INNER JOIN populations AS p2 ON p1.country_code = p2.country_code;
(在本截图所示的表格上)
当我试图删除关键字INNER时,它是错误的。是因为SQL中不存在JOIN吗?
谢谢,干杯。
