presto字符串转浮点数、整数处理

1. 相除保留小数位

Presto中两个整数相除会结果为零。当我们相除的两个数都为整数时，比如我想用两个count（）结果相除，想保留n为小数

select count(*)*1.00 / count(*) from student;
结果就会自动保留两位小数，想要n位就1.后面n个零

2. 字符串转整数

select cast (bj_score as bigint), bj_score from dcs_input_tab_bj_score

3. 字符串转浮点

select cast (bj_score as double), bj_score from dcs_input_tab_bj_score

4. round(x, d) 保留d位小数，对后面的做四舍五入

select round(976.56374123, 5); --对第5位后的做四舍五入

5. is_nan(x) 判断浮点数是为为空，返回true或者false

select is_nan(976.56374123);

6. rand() 随机生成一个随机浮点数

select rand(); 

标签：count,presto,浮点数,bj,score,相除,字符串,select
来源： https://blog.csdn.net/zhuchunyan_aijia/article/details/122419042