这个在MS SQL中工作得很好。它将varchar转换为两个小数限制浮点数的结果。

Select field1, cast(Try_convert(float,(Count(field2)* 100) / 
Try_convert(float, (Select Count(*) From table1))) as decimal(10,2)) as new_field_name 
From table1 
Group By field1, field2;

SELECT Grade, GradeCount / SUM(GradeCount)
FROM (SELECT Grade, COUNT(*) As GradeCount
      FROM myTable
      GROUP BY Grade) Grades

以下操作应该可以工作

ID - Key
Grade - A,B,C,D...

编辑:移动* 100并添加1.0以确保它不做整数除法

Select 
   Grade, Count(ID) * 100.0 / ((Select Count(ID) From MyTable) * 1.0)
From MyTable
Group By Grade

我也遇到过类似的问题。您应该能够得到乘以1.0而不是100的正确结果。参见附图示例

选择Grade， (Count(Grade)* 1.0 / (Select Count(*) From MyTable))作为来自MyTable Group By Grade的分数

你们需要在成绩领域分组。这个查询应该为您提供在几乎任何数据库中要查找的内容。

    Select Grade, CountofGrade / sum(CountofGrade) *100 
    from
    (
    Select Grade, Count(*) as CountofGrade
    From Grades
    Group By Grade) as sub
    Group by Grade

您应该指定您正在使用的系统。

你可以在你的from查询中使用子选择(未经测试，不确定哪个更快):

SELECT Grade, COUNT(*) / TotalRows
FROM (SELECT Grade, COUNT(*) As TotalRows
      FROM myTable) Grades
GROUP BY Grade, TotalRows

Or

SELECT Grade, SUM(PartialCount)
FROM (SELECT Grade, 1/COUNT(*) AS PartialCount
      FROM myTable) Grades
GROUP BY Grade

Or

SELECT Grade, GradeCount / SUM(GradeCount)
FROM (SELECT Grade, COUNT(*) As GradeCount
      FROM myTable
      GROUP BY Grade) Grades

你也可以使用存储过程(Firebird语法不好意思):

SELECT COUNT(*)
FROM myTable
INTO :TotalCount;

FOR SELECT Grade, COUNT(*)
FROM myTable
GROUP BY Grade
INTO :Grade, :GradeCount
DO
BEGIN
    Percent = :GradeCount / :TotalCount;
    SUSPEND;
END