Question

May I ask someone to help me write this in LINQ,

 DataTable dt = new DataTable();

            DataColumn dcValue = new DataColumn();
            dcValue.ColumnName = "value";

            DataColumn dvDisplay = new DataColumn();
            dvDisplay.ColumnName = "display";

            DataColumn dvIsDefualt = new DataColumn();
            dvIsDefualt.ColumnName = "isDefalt";

            dt.Columns.Add(dcValue,int);
            dt.Columns.Add(dvDisplay,string);
            dt.Columns.Add(dvIsDefualt,bool);

            this.tipRacuna.DataSource = ds.Tables[0];
            this.tipRacuna.ValueMember = "value";
            this.tipRacuna.DisplayMember = "display";

            this.tipRacuna.SelectedValue =  findDefault(dt);//linq to find first value with default = true;    


        }
        private int findDefault(DataTable dtt)
            {
                int i= 0;

            foreach (DataRow  dr in dtt.Rows)
            {
                if (bool.Parse(dr["isDefalt"].ToString()))
                {
                    return int.Parse(dr["value"].ToString());
                }
            }
                return i;
            }

As I am getting more involved in C# and programming at all, I am getting more intersting in LINQ queries.
In begins I always skip LINQ taking argument as I know TSQL no needs for another Query language, but when I see how many lines of code i can save using LINQ i start learning it.

Answer 1

Assuming that your DB columns are strongly-typed (best):

dtt.AsEnumerable().Where( dr => dr.Field<bool>("isDefault" ) )
    .Select( dr => dr.Field<int>( "value" ) ).FirstOrDefault();

With type conversion:

dtt.AsEnumerable().Where( dr => Convert.ToBoolean( dr["isDefault"] ) )
    .Select( dr => Convert.ToInt32( dr["value"] ) ).FirstOrDefault();

With parsing:

dtt.AsEnumerable().Where( dr => bool.Parse( dr["isDefault"].ToString() ) )
    .Select( dr => int.Parse( dr["value"].ToString() ) ).FirstOrDefault();

Note that I have corrected the spelling of “isDefalt” to “isDefault”.