SUM
函数说明
SUM()
聚合函数用于计算一组值的和(NULL 值被忽略)。
函数语法
> SUM(expr)
参数释义
参数 | 说明 |
---|---|
expr | 任何数值类型与字符串列的列名 |
返回值
返回 expr
列的数值的和,若输入参数为 Double
类型,则返回值为 Double
,否则为整数类型。
如果没有匹配的行,则返回 NULL
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 sum(col_1c) from tbl1;
+-------------+
| sum(col_1c) |
+-------------+
| 21 |
+-------------+
> select sum(col_1d) as c1 from tbl1 where col_1d < 13 group by col_1e order by c1;
+------+
| c1 |
+------+
| 8 |
| 10 |
| 18 |
| 21 |
+------+