如何知道，如果一个领域是数字在LINQ to SQL [英] How to know if a field is numeric in Linq To SQL

问题描述

我需要选择一个表行，其中一列的值是数字，任何帮助

I need to select the rows of a table where a column value is numeric, any Help?

编辑：我有varchar列，我需要选择。那些是数字和不属于那些

I have a varchar column and I need to select the ones that are numbers and the ones that are not.

编辑2：Integer.TryParse不能使用，因为它不能被转换到SQL

EDIT 2: Integer.TryParse cannot be use because it cannot be translate to SQL.

推荐答案

我不知道是否有用于int.TryParse（）在LinqToSQL映射，但你很可能通过执行查询做它在两个步骤，铸造到一个列表，然后选择与LinqToObjects名单出来

I don't know if there is a mapping for int.TryParse() in LinqToSQL, but you could probably do it in two steps by performing the query, casting to a List, then selecting out of the list with LinqToObjects.

int i;
var query = context.Table.ToList();
var intQuery = query.Where( t => int.TryParse( t.Column, out i ) );

您可能想要看的动态LINQ 了。这将允许你这样做是这样的：

You might want to look at Dynamic LINQ, too. That would allow you to do something like:

var query = context.Table.Where( "IsNumeric(Column)" );

修改动态LINQ是VS2008的代码示例用，挂在斯科特Guthrie的博客，我已经上面链​​接。

EDIT Dynamic LINQ is available in the VS2008 Code Samples, linked to from Scott Guthrie's blog, which I've linked above.

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