sql 分组求和 、分组求平均

SELECT device_type_name, AVG(rate)  FROM tb_device_rate GROUP BY device_type_name  

SELECT device_type_name, SUM(rate)  FROM tb_device_rate GROUP BY device_type_name  

SELECT device_type_name, AVG(rate) AS rate  FROM tb_device_rate GROUP BY device_type_name  


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