sqlite中的2个连接查询

有人能帮我吗？我是数据库和查询新手。我正在使用sqlite；我的数据库包含两个表。边和节点。 表格如下：

nodes
_______________________
NO     name      family
9808   antony    bits
6757   saly      wood



edges
_______________________
ID     Source    Target
1      9808      6757
2      9808      6757
3      6757      9808
4      6757      9808
5      9808      6757

查询应使用名称和族以及名称和族替换源和目标，然后计算每个边的频率，结果如下：

Source            target           frequency
"antony bits"     "saly wood"       3
"saly wood"       "antony bits"     2

从.mode列开始，然后运行此查询：

select a.name||' '||a.family as source, b.name||' '||b.family as target, count() as freq from edges as c
left join nodes as a on c.source = a.NO
left join nodes as b on c.target = b.NO
group by source, target
order by freq desc ;

输出为：

source       target       freq
-----------  ----------   ----------
antony bits  saly wood    3
saly wood    antony bits  2

诀窍是在源列和目标列上双击表