为什么说列定义不明确?

Question

select a.id_progdi, a.nama_progdi, avg(b.ipk)  
from tb_ipk b 
join tb_mahasiswa c on b.nim = c.nim 
join tb_progdi a on c.id_progdi = a.id_progdi  
group by id_progdi

Answer 1

您有多个id_progdi，因此可能不知道在group by中引用哪一个。将其更改为group by a.id_progdi

Answer 2

在分组依据中，您应该添加表别名，因为您在多个表中具有相同的列名，并且数据库引擎需要知道您要引用哪个列名

select a.id_progdi, a.nama_progdi, avg(b.ipk)  
from tb_ipk b
join  tb_mahasiswa c  on b.nim = c.nim 
join tb_progdi a on c.id_progdi = a.id_progdi  
group by a.id_progdi, a.nama_progdi

Answer 3

也许您在多个表中id_progdi在分组依据中使用表别名。