Question

I have a table that has (for example) 4 columns.

• pk_table_id INT NOT NULL
• username VARCHAR(100) NOT NULL
• start_date DATETIME NOT NULL
• end_date DATETIME NULL

My requirement is to return all rows in descending order of end_date – BUT the NULL values must be first, and then descending order of start_date.

I’ve done it in SQL – but could someone assist me with a LINQ version to do this?

This is the SQL query we use:

    SELECT [person_employment_id]
       , [party_id]
       , [employer_name]
       , [occupation]
       , [telephone]
       , [start_date]
       , [end_date]
       , [person_employment_type_id]
       , [person_employment_end_reason_type_id]
       , [comments]
       , [deleted]
       , [create_user]
       , [create_date]
       , [last_update_user]
       , [last_update_date]
       , [version]
    FROM [dbo].[person_employment] 
   WHERE ([party_id]=@party_id)
   ORDER BY ISNull([end_date],'9999-DEC-31') DESC, [start_date] DESC

Answer 1

For this problem, you could do a null check on the end_date and use that result as the ordering. So you don’t need to use the same SQL constructs to achieve this, but rather use one more natural in your language of choice (C# I’m assuming).

var query =
    from row in dc.Table
    let isEndDateNull = row.end_date == null
    orderby isEndDateNull descending, row.start_date descending
    select row;