Question

I have the following table:

ID   ActualDt   DueDt     Flag
--   -------    -------   ----    
1    01/03/12   09/13/12   Y
2    NULL       07/12/12   Y 
3    NULL       09/12/12   N
4    02/03/12   01/13/12   N

I need to mark Flag as Y for the following conditions:

1) If ActualDt is not null and DueDt is not null and DueDt > ActualDt

2) If ActualDt is null and DueDt is past due based on current date

Otherwise, Flag = N

Note that ActualDt is a string

How would I program this in t-sql

I know I need a case statement.

Answer 1

You need an update statement:

update t
    set flag = (case when ActualDt is not null and DueDt is not null and
                          DueDt > cast(ActualDt as date)
                     then 'Y'
                     when ActualDt is null and DueDt is not null and
                          DueDt > cast(CURRENT_TIMESTAMP as date)
                     then 'Y'
                     else 'N'
                end)

This query assumes that the format of the date matches the default format for the database. My database is set to US standards, so ’01/03/12′ is interpreted as Jan 3, 2012.