SQL SUM()
SUM() 返回数值列总和（忽略 NULL），常配合 GROUP BY 做分组汇总。
Key PointsSQL,SUM,求和
讲解
SUM() 返回数值列总和（忽略 NULL），常配合 GROUP BY 做分组汇总。
示例
SQL
SELECT SUM(count) AS total FROM access_log;
SELECT site_id, SUM(count) AS total
FROM access_log GROUP BY site_id;Output
total
-----
375
site_id total
------- -----
1 45
2 100
3 230讲解
SUM() 返回数值列总和（忽略 NULL），常配合 GROUP BY 做分组汇总。
示例
SQL
SELECT SUM(count) AS total FROM access_log;
SELECT site_id, SUM(count) AS total
FROM access_log GROUP BY site_id;Output
total
-----
375
site_id total
------- -----
1 45
2 100
3 230