postgreSQL 小数点惹得祸
发布时间:2020-12-13 16:38:49 所属栏目:百科 来源:网络整理
导读:按每个活动的达标率展示 示例表 activity 如下: activity | need | already | user A | 1000 | 1 | U_A B | 500 | 1 | U_B B | 500 | 1 | U_B A | 1000 | 1 | u_A 开始写SQL: select activity, count ( 1 ),need,round( count ( 1 ):: NUMERIC / need:: NUME
按每个活动的达标率展示 示例表 activity 如下: activity | need | already | user
A | 1000 | 1 | U_A
B | 500 | 1 | U_B
B | 500 | 1 | U_B
A | 1000 | 1 | u_A
开始写SQL: select activity,count(1),need,round(count(1)::NUMERIC / need::NUMERIC,2 ) already_rate from activity where activity in ('A','B') group by activity,need order by already_rate desc,activity asc;
结果:
| activity | count | need | already_rate |
| A | 2 | 1000 | 0.00 |
| B | 2 | 500 | 0.00 |
上边应该是B 排在A前边才对,且already_rate 也出错了,主要是由于精度没有掌握好,need数如果不都一样,比较随机,这个时候该怎么办呢? select activity,length(need::text) ) already_rate from activity where activity in ('A',activity asc;
结果:
| activity | count | need | already_rate |
| B | 2 | 500 | 0.004 |
| A | 2 | 1000 | 0.0020 |
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