select tableA,group_concat(tableB) tableB from tb group by tableA;

------解决方案--------------------
SELECT  
tableA,group_concat(tableB)tableB
FROM tb
GROUP BY tableA;

------解决方案--------------------
 select tableA, group_concat(tableB)
  from yourTable
  group by tableA

------解决方案--------------------
探讨


SQL code
select tableA,group_concat(tableB) tableB from tb group by tableA;