AVG

声明

AVG(([DISTINCT | ALL] expr)

说明

返回指定组中的平均值，空值被忽略。DISTINCT 选项可用于返回 expr 的不同值的平均值。如果找不到匹配的行，则 AVG() 返回 NULL。

示例

SELECT * FROM oceanbasetest;
+----+------+------+
| id | ip   | ip2  |
+----+------+------+
|  1 |    4 | NULL |
|  3 |    3 | NULL |
|  4 |    3 | NULL |
+----+------+------+
3 rows in set (0.002 sec)

SELECT avg(ip2), avg(ip), avg(distinct(ip)) FROM oceanbasetest;
+----------+---------+-------------------+
| avg(ip2) | avg(ip) | avg(distinct(ip)) |
+----------+---------+-------------------+
|     NULL |  3.3333 |            3.5000 |
+----------+---------+-------------------+
1 row in set (0.001 sec)

SELECT avg(distinct(ip)),avg(ip),avg(ip2) FROM oceanbasetest;
+-------------------+---------+----------+
| avg(distinct(ip)) | avg(ip) | avg(ip2) |
+-------------------+---------+----------+
|            3.5000 |  3.3333 |     NULL |
+-------------------+---------+----------+
1 row in set (0.001 sec)