如何获取数字列的确切类型。规模和精度？ [英] How to get the exact type of numeric columns incl. scale and precision?

问题描述

有没有办法知道 DataTable 中列的确切类型？现在我这样做：

Is there a way to know the exact type of a column in a DataTable? Right now I am doing this:

DataTable st = dataReader.GetSchemaTable();
foreach (DataColumn col in st.Columns)
{
   var type = col.DataType;
}

现在使用 type.Name 我可以找到它是否是一个数字（ int 或 decimal ..）或 string 但问题是我需要确切的类型，例如，如果在数据库中让列价格是 NUMBER（4,3）然后在我的代码中，我只能将类型'Decimal'，而没有关于Format 4,3 的信息。

Now with type.Name I am able to find if it is a number(int or decimal..) or string but the problem is that I need the exact type, for example if in database let say column Rate is NUMBER(4,3) then here in my code I am only getting type as 'Decimal' and no information about the Format 4,3.

现在，我需要根据他们的类型格式化值，例如。如果 Rate = 1.4 ，应显示为 0001.400 （根据格式 NUMBER（4 ，3））。因此，由于我没有信息，我无法进一步处理这些值。有没有知道相同？

Now the requirement is I need to format the values as per their type for eg. if Rate=1.4 it should be shown as 0001.400 (according to the Format NUMBER(4,3)). Hence here since I do not have info I am not able to process the values further. Is there anyway to know the same?

谢谢

推荐答案

你可以使用 NumericPrecision 和 NumericScale ：

using (var con = new SqlConnection(Properties.Settings.Default.RM2ConnectionString))
using (var cmd = new SqlCommand("SELECT * FROM dbo.Test", con))
{
    con.Open();
    using (var reader = cmd.ExecuteReader())
    using (var schemaTable = reader.GetSchemaTable())
    {
        foreach (DataRow row in schemaTable.Rows)
        {
            string column = row.Field<string>("ColumnName");
            string type = row.Field<string>("DataTypeName");
            short precision = row.Field<short>("NumericPrecision");
            short scale = row.Field<short>("NumericScale");
            Console.WriteLine("Column: {0} Type: {1} Precision: {2} Scale: {3}", column, type, precision, scale);
        }
    }
}

更多信息： GetSchemaTable

More informations: GetSchemaTable

我已经用一个新的表单测试了一个单列 NumberColumn 类型 numeric（4，3）：

I have tested it with a fresh table with a single column NumberColumn of type numeric(4, 3):

Column: NumberColumn Type: decimal Precision: 4 Scale: 3

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