I have DataTable with two columns Author and Bookname.
I want to check if the given string value Author already exists in the DataTable. Is there some built in method to check it, like for Arrays array.contains?
5 Answers
You can use LINQ-to-DataSet with Enumerable.Any:
String author = "John Grisham";
bool contains = tbl.AsEnumerable().Any(row => author == row.Field<String>("Author"));
Another approach is to use DataTable.Select:
DataRow[] foundAuthors = tbl.Select("Author = '" + searchAuthor + "'");
if(foundAuthors.Length != 0)
{
// do something...
}
Q: what if we do not know the columns Headers and we want to find if any cell value
PEPSIexist in any rows'c columns? I can loop it all to find out but is there a better way? –
Yes, you can use this query:
DataColumn[] columns = tbl.Columns.Cast<DataColumn>().ToArray();
bool anyFieldContainsPepsi = tbl.AsEnumerable()
.Any(row => columns.Any(col => row[col].ToString() == "PEPSI"));
6 Comments
Paul Alexander
Out of the two solutions, which would be faster?
Tim Schmelter
@PaulAlexander: there isn't a great difference. But the old
DataTable.Select syntax is limited whereas LINQ can use the full .NET framework or custom methods. So only if you are stuck to .NET 2 you should use DataTable.Select, otherwise i'd always prefer LINQ
HerrimanCoder
If you care about performance and have large datasets,
tbl.Select() is dramatically faster than the other approaches.
Chandan Kumar
@TimSchmelter - Great Tim. But if user don't know the column name but still want to get all rows which is matching the search value how it can be done ?
|
You can use Linq. Something like:
bool exists = dt.AsEnumerable().Where(c => c.Field<string>("Author").Equals("your lookup value")).Count() > 0;
Comments
DataRow rw = table.AsEnumerable().FirstOrDefault(tt => tt.Field<string>("Author") == "Name");
if (rw != null)
{
// row exists
}
add to your using clause :
using System.Linq;
and add :
System.Data.DataSetExtensions
to references.
Comments
You should be able to use the DataTable.Select() method. You can us it like this.
if(myDataTable.Select("Author = '" + AuthorName.Replace("'","''") + '").Length > 0)
...
The Select() funciton returns an array of DataRows for the results matching the where statement.
Comments
you could set the database as IEnumberable and use linq to check if the values exist. check out this link
LINQ Query on Datatable to check if record exists
the example given is
var dataRowQuery= myDataTable.AsEnumerable().Where(row => ...
you could supplement where with any
table.Any(t => t.Author == author);