LINQ SELECT FIRST ROW

Question

Hi,

How can I select first row in a linq select statement without using foreach?

I use foreach and then break; but it has to be a better way?

I like to get the value in first row; plus check if no row is found. My problem is to get the value without foreach statement.

What I do is to find a value in my DataTable and I know the row is uniqe; so I like to do a select and get the value; plus do a check if there is no hit to be safe... :)

This is the code I use now, see below

Thank you, Rune

var var_QUERY_linq = 
    from vm_TABLE_PK in vco_DataTable_PK.AsEnumerable()
    where vm_TABLE_PK.Field<Int32>( "MyField_Int32" ) == vmp_ROW_Counter_Int32
    select vm_TABLE_PK;

foreach ( DataRow o_DataRow in var_QUERY_linq )
{
       vmp_Return_string = o_DataRow.Field<string>( "Myfield_nvarchar" );

       break;
}

Answer 1

Just use .FirstOrDefault()

var var_QUERY_linq = (
    from vm_TABLE_PK in vco_DataTable_PK.AsEnumerable()
    where vm_TABLE_PK.Field<Int32>( "MyField_Int32" ) == vmp_ROW_Counter_Int32
    select vm_TABLE_PK).FirstOrDefault();

if(var_QUERY_linq != null)
{
    //There is a record
}

Answer 2

I assume MyField is the field you want to get value of

var result = vm_Table_Pk.DefaultIfEmpty().First().MyField;

You can also set the default result other than NULL. Like :

var result = vm_Table_Pk.DefaultIfEmpty("Missing").First().MyField;

And don't worry Intellisense will help you along this way.

Answer 3

I expereinced an issue with the order of the item (OrderBy) when I use FirstOrDefault to find the first item from the list.

I would suggest you to use TAKE to get the first item:

var_QUERY_linq.Take(1).FirstOrDefault()

*Always use sql profiler if possible to check the query that is sent to SQL server.

Answer 4

.First() will take just the first or .Single() will take the first and raise exception if there is more