在表/视图中添加字段

Question

我想通过取多个值的平均值来计算sql表/视图中的平均值，并希望按另一列分组。

例如，在所附的excel工作表中，当块ID相同时，我想从SG（Calc）字段计算平均密度。

+-----------------------------------+-----------+--------------+
| BlockID                           | SG (Calc) | Ave. Density |
+-----------------------------------+-----------+--------------+
| SESS_5835_01_OXD_SAP_AL01         |      1.86 |              |
| SESS_5835_01_OXD_SAP_AL01         |      1.71 |              |
| SESS_5835_01_OXD_SAP_MG04         |      2.08 |              |
| SESS_5835_01_OXD_SAP_MG04         |      2.14 |              |
| KCD_5897.5_01_OXD_TRA_VG02        |      2.74 |              |
| KCD_5897.5_01_OXD_TRA_VG02        |      2.74 |              |
| KCD_5897.5_01_OXD_TRA_VG02        |      2.51 |              |
| KCD_5895_01_OXD_TRA_MG06          |      3.19 |              |
| KCD_5895_01_OXD_TRA_MG06          |      3.02 |              |
| SESS_58932.5_01_OXD_TRA_MG05      |      2.24 |              |
| SESS_58932.5_01_OXD_TRA_MG05      |      2.27 |              |
+-----------------------------------+-----------+--------------+

Answer 1

这将起作用：

select a.*,avg(SG(Calc)) from table_name a group by a.BlockID;

Answer 2

您是否正在寻找窗口功能？

select a.*, avg(SG) over (partition by blockid) as avg_block_density
from t a ;