我希望将FULL OUTER JOIN的结果用作另一个表上的FULL OUTER JOIN表。我应该使用什么语法?T1 FULL OUTER JOIN T2 on T1.id = T2.id ==> Let this be named X
X FULL OUTER JOIN T3 on X.id任何替代的方法,这也是可以的。
103 || B | 2 | (null) | (null) |但根据我目前的声明|| B | 3 | 5 | 105 |到目前为止,按m,d顺序订购的尝试都失败了outer join t on kombi.d = t.d and kombi.m = t.m) as result) order by result.
数据库: MySqlcreate table classid int(10) not null,select * from Student inner join class on Student.ci = class.id
Explain plan似乎只对表使用索引&它对其他表使用全表扫描。索引显示在EXPLAIN PLAN中的可能键中,但未使用...
我试图用一个外键字段连接两个与django相关的表。models.ForeignKey(User)questions = Question.objects.filter(vote__creator=3).values()select * from questions as t1 join votes as t2 on t1.id=question_id where creator_id| id | que