Using Nested IF ELSE statements in sql -

when 1 of following conditions met, want code go next execution step:

1. first name, last name , dob : 3 not blank
2. id , dob not blank
3. ssn , dob not blank
4. id , group number not blank

below code have. when run providing first name, last name , dob (condition 1 satisfied), still fails saying condition 4 not met. can tell me doing wrong?

if ( ( @firstname null          or len(ltrim(@firstname)) = 0 )       , ( @lastname null              or len(ltrim(@lastname)) = 0 )       , ( @dob null ) )    begin        insert @validationerror                    (errormessage)        values      ( 'first name, last name , date of birth must specified.'        )    end  else    begin        if ( @dob null             , @id null )          begin              insert @validationerror                          (errormessage)              values      ( 'date of birth , id must specified.' )          end        else          begin              if ( @dob null                   , @ssn null )                begin                    insert @validationerror                                (errormessage)                    values      ( 'date of birth , ssn must specified.' )                end              else                begin                    if ( @id null                         , @groupnumber null )                      begin                          insert @validationerror                                      (errormessage)                          values      ( 'id , group number must specified.' )                      end                end          end    end  

a case statement simpler:

insert @validationerror  (errormessage)   select case when criteria1 'first name, last name , date of birth must specified.'             when criteria2 'date of birth , id must specified.'             when criteria3 'date of birth , ssn must specified.'               when criteria4 'id , group number must specified.'                end 

as far error in syntax, you've got extraneous begin , end, believe following work:

if ( ( @firstname null or len(ltrim(@firstname)) = 0 )       , ( @lastname null or len(ltrim(@lastname)) = 0 )       , ( @dob null ) )      begin            insert @validationerror                        (errormessage)            values      ( 'first name, last name , date of birth must specified.')      end  else if ( @dob null , @id null )      begin          insert @validationerror                      (errormessage)          values      ( 'date of birth , id must specified.' )      end  else if ( @dob null , @ssn null )      begin          insert @validationerror                      (errormessage)          values      ( 'date of birth , ssn must specified.' )      end  else if ( @id null , @groupnumber null )      begin          insert @validationerror                      (errormessage)          values      ( 'id , group number must specified.' )      end