How do I compare a string value in C#

Question

I am pulling data from a SQL database, I am filling in missing data that is blank or missing with the following statement.

string.Join(
    ",",
    from
        r in siteData.Rows.OfType<DataRow>() 
    select
        r[28] == DBNull.Value ? "null" : r[28]);

I would like to replace a value of -9999 with a blank value as well.

Answer 1

In SQL, use CASE WHEN :

SELECT
    CASE WHEN someValue = -9999 THEN '' ELSE someValue END AS colName

In Linq, just change your ternary:

siteData.Rows.OfType<DataRow>().Select( r => r[28] == DBNull.Value || r[28] == -9999 ? "" : r[28] )

Answer 2

You can do it this way:

string.Join(
    ",",
    from
        r in siteData.Rows.OfType<DataRow>() 
    select
        string.IsNullOrEmpty((string)r[28]) ? "null" : r[28]);