[英]SQL Server query from 2 tables with grouping and average calc
我在SQL Server数据库中有2个表:
我需要的是返回按[opt_1]和[opt_2]分组记录的表的查询,如下所示:
[opt_1],
[opt_2],
{count of such records from table_1},
{count of such records from table_2, by [id]},
{average [result] from table_2, by [id]}
最好的方法是什么?
您可以使用join
和group by
;
select t1.opt_1,t2.opt_2,count(t1.id),AVG(t2.result) from table1 t1
inner join table2 t2 ON t1.id = t2.id
group by t1.opt_1,t2.opt_2
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