Question

我有两个ms sql server表，其列类型为float（非null）。

当我在这两个表中联合ALL时

SELECT [float_column], 
       Min(sourcename) AS ExistsInFile 
FROM   (SELECT [float_column], 
               'File 1' AS SourceName 
        FROM   table1 
        WHERE  column1 = 'abc' 
        UNION ALL 
        SELECT [float_column], 
               'File 2' AS SourceName 
        FROM   table2 
        WHERE  column1 = 'abc') x 
GROUP  BY [float_column] 
HAVING Count(DISTINCT sourcename) <> 2

它给了我以下输出，但它不应该显示任何差异，因为两个值都相同。

float_Column     |    ExistsInFile
-53590187.62            File 2
-53590187.62            File 1

这是因为浮动类型吗？任何帮助将不胜感激！

Answer 1

是的，问题是浮动。这里的问题不是union all。问题是group by。

浮点数可能与表示数字的最小位不同 - 您无法看到差异。因此，对于您的问题，只需将所有内容转换为小数：

SELECT CAST([float_column] as DECIMAL(12, 2), 
       Min(sourcename) AS ExistsInFile 
FROM   (SELECT [float_column], 
               'File 1' AS SourceName 
        FROM   table1 
        WHERE  column1 = 'abc' 
        UNION ALL 
        SELECT [float_column], 
               'File 2' AS SourceName 
        FROM   table2 
        WHERE  column1 = 'abc') x 
GROUP BY CAST([float_column] as DECIMAL(12, 2) 
HAVING Count(DISTINCT sourcename) <> 2 ;

浮点值UNION ALL查询

1 个答案: