sql - 我怎样才能在一个查询中做到这一点

Question

表名：words
字段：wId、lemma、relatedId
数据：
0 apple 1
1 pie -1

预期结果：
wId = 0
引理 = apple
relatedWord = pie

Answer 1

这个查询可以做你想做的事。据我了解，您的表格单词包含relatedld 和 wld 之间的外键。所以这个查询应该满足您的需求：

SELECT t1.wld as wld, 
       t1.lemma as lemma, 
       t2.wld as relatedWorld
FROM words t1 JOIN words t2 ON t1.relatedld = t2.wld;

Answer 2

你可以参考这里

详情如下：

create table words (wId integer, 
                    lemma varchar(100), 
                    relatedId Integer);
Insert Into words values(0,'apple',1),(1,'pie',-1);

select t1.WID,t1.lemma as Lemma,t2.lemma as relatedWord 
from words t1,words t2
where t1.RelatedID = t2.WID