SQL select where column clause

Question

I have a table as follows

date1   |  date2  | datechoice

1-5-17    2-6-17      date2

Datechoice can either be date1 or date2. And I want to first look at the datechoice column to decide which column to use in the where statement.

Example Pseudo Code:

CASE WHEN datechoice ='date2' 
     THEN where date2 >= 2-2-17 AND where date2 <= 2-9-17 
     ELSE where date1 >= 2-2-17 AND where date1 <= 2-9-17

How can I do this?

Answer 1

WHERE (datechoice ='date1' and date1 >= '2017-02-02' AND date1 <= '2017-02-09')
   OR (datechoice ='date2' and date2 >= '2017-02-02' AND date2 <= '2017-02-09') 

Answer 2

This may be suspect for index use. I can't see how an index could be used since we have both dates conditinally being considered. An OR approach or two queries and a union may actually be more efficient.

WHERE case when datechoice = 'date1' then date1 
            when datechoice = 'date2' then date2 end 
            between '2017-02-02' and '2017-02-09'

Careful with between use I'm assuming date1 and date2 are actually date fields with no time component if time exists then you may have records missing on the upper boundary.