C# 从 DataRow [] 集合中选择一个 DataRow
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Select a DataRow from a DataRow [] collection
提问by Sora
My code :
我的代码：
DataRow[] row = ByTotalTemplate.Select("TEMPLATE_ID=" + DisTemplateID);
A row contains TEMPLATE_ID,MIN_AMOUNT,MAX_AMOUNTand DISCOUNT
一行包含TEMPLATE_ID，MIN_AMOUNT，MAX_AMOUNT和DISCOUNT
Now I want to select a row where a given amount is between MIN_AMOUNTand MAX_AMOUNT
现在我想选择给定金额介于MIN_AMOUNT和之间的行MAX_AMOUNT
I tried to do this :
我试图这样做：
DataRow amountRow = row.Select("MIN_AMOUNT<" + quantity + " AND MAX_AMOUNT>" + quantity);
but this didn't work.
但这没有用。
采纳答案by Tim Schmelter
Instead of fiddling around with the expression syntax i would use Linq:
我会使用 Linq，而不是摆弄表达式语法：
IEnumerable<DataRow> rows = ByTotalTemplate.AsEnumerable()
.Where(r => r.Field<int>("TEMPLATE_ID") == DisTemplateID
&& r.Field<int>("MIN_AMOUNT") < quantity
&& r.Field<int>("MAX_AMOUNT") > quantity);
If you want a new DataTable with the filtered result:
如果你想要一个带有过滤结果的新数据表：
DataTable table = rows.CopyToDataTable();
Note that CopyToDataTablethrows an exception if there are no rows since it must derive the columns from the rows. So you have to check it before. You could use:
请注意，CopyToDataTable如果没有行，则抛出异常，因为它必须从行派生列。所以你必须先检查它。你可以使用：
DataTable table = ByTotalTemplate.Clone();
if(rows.Any())
table = rows.CopyToDataTable();
If you want an array instead:
如果你想要一个数组：
DataRow[] rowArray = rows.ToArray();
If you just want the first row:
如果你只想要第一行：
DataRow row = rows.FirstOrDefault(); // can be null if there is no matching row
Btw, your problem was that you used DataTable.Selecton a DataRow[]
顺便说一句，你的问题是你DataTable.Select在DataRow[]
回答by gzaxx
You have to select rows again from your DataTableif you want to use Select()method
DataTable如果要使用Select()方法，则必须再次从您的行中选择行
DataRow[] rowsBetween = ByTotalTemplate.Select("TEMPLATE_ID = " + DisTemplateID + " AND MIN_AMOUNT < " + qunatity + " AND MAX_AMOUNT > " + qunatity);
回答by sangram parmar
try this
尝试这个
DataRow[] row = ByTotalTemplate.Select("TEMPLATE_ID=" + DisTemplateID);
//
//some use of **row** here
//than after select record from **row**
DataRow[] amountRow = row.CopyToDataTable().Select("MIN_AMOUNT < " + qunatity + " AND MAX_AMOUNT > " + qunatity);
