如何在运行时根据其他表中的值添加新列？

SELECT table2.t1_id,table1.name,
sum(case when month='Jan' then amount else 0 end) as jan,
sum(case when month='feb' then amount else 0 end) as feb,
sum(case when month='Mar' then amount else 0 end) as Mar
from table2 inner
join table1 on table1.t1_id=table2.t1_id group by table2.t1_id,name
order by table2.t1_id;