AVG
函数说明
AVG() 是聚合函数的一种，计算了参数列的算术平均值。
函数语法
> AVG(expr)
参数释义
| 参数 | 说明 |
|---|---|
| expr | 任何数值类型的列的列名 |
返回值
以 Double 类型返回该列的算术平均值。
若输入参数为空，则返回 NaN 值。
示例
> drop table if exists tbl1,tbl2;
> create table tbl1 (col_1a tinyint, col_1b smallint, col_1c int, col_1d bigint, col_1e char(10) not null);
> insert into tbl1 values (0,1,1,7,"a");
> insert into tbl1 values (0,1,2,8,"b");
> insert into tbl1 values (0,1,3,9,"c");
> insert into tbl1 values (0,1,4,10,"D");
> insert into tbl1 values (0,1,5,11,"a");
> insert into tbl1 values (0,1,6,12,"c");
> select avg(col_1c) from tbl1;
+-------------+
| avg(col_1c) |
+-------------+
| 3.5000 |
+-------------+
> select sum(col_1d) as s1,avg(col_1d) as a3 from tbl1 group by col_1e order by s1 desc;
+------+---------+
| s1 | a3 |
+------+---------+
| 21 | 10.5000 |
| 18 | 9.0000 |
| 10 | 10.0000 |
| 8 | 8.0000 |
+------+---------+
> select avg(col_1d) as a1 from tbl1 where col_1d < 13 group by col_1e order by a1;
+---------+
| a1 |
+---------+
| 8.0000 |
| 9.0000 |
| 10.0000 |
| 10.5000 |
+---------+