c# - 检查数据表中是否存在值？

Question

我有包含两列作者和书名的数据表。

我想检查给定的字符串值 Author 是否已经存在于 DataTable 中。是否有一些内置方法来检查它，比如数组 array.contains？

Answer 1

您可以使用 LINQ-to-DataSet与 Enumerable.Any :

String author = "John Grisham";
bool contains = tbl.AsEnumerable().Any(row => author == row.Field<String>("Author"));

另一种方法是使用 DataTable.Select :

DataRow[] foundAuthors = tbl.Select("Author = '" + searchAuthor + "'");
if(foundAuthors.Length != 0)
{
    // do something...
}

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Q: what if we do not know the columns Headers and we want to find if any cell value PEPSI exist in any rows'c columns? I can loop it all to find out but is there a better way? –

是的，你可以使用这个查询:

DataColumn[] columns = tbl.Columns.Cast<DataColumn>().ToArray();
bool anyFieldContainsPepsi = tbl.AsEnumerable()
    .Any(row => columns.Any(col => row[col].ToString() == "PEPSI"));