SQL Server 2008 CASE statement gives invalid column error

Question

As part of a larger SQL query, I am creating a temporary table to store related items from another (temporary) table. The select portion of the insert statement uses a CASE statement to fill the final column ( labSample ) with either a 1 or 0 based on the value of the dataSource column. SSMS returns an invalid column error for the reference to dataSource in the labSample column. I can't for the life of me work out why this error is occurring - is this a syntax error or am I just missing something?

The naming convention used below is an underscore preceding the column name are the new columns in the #related table, while column names without underscore originate in the #temp_trace table (except dataSource and labSample columns which are only in the #related table).

I'd really appreciate a bit of help with this one!

create table #related (_tr_id int, _mp_id int, _sta_id int, _tr_number_s nvarchar(20),
    _tr_tstamp_ts datetime, _tr_team_s nvarchar(100), _tr_comment_s nvarchar(512),
    _kld_id_medium int, _kld_id_reason int, _kld_id_typeofsmpl int, _sp_id int, 
    _sa_id int, _sa_depth_fl float, _fr_number_l int, dataSource nvarchar(128), labSample bit)

insert into #related (_tr_id, _mp_id, _sta_id, _tr_number_s,
    _tr_tstamp_ts, _tr_team_s, _tr_comment_s,
    _kld_id_medium, _kld_id_reason, _kld_id_typeofsmpl, _sp_id, _sa_id, _sa_depth_fl,
    _fr_number_l, dataSource, labSample)
select
    tt.tr_id as _tr_id,
    tt.mp_id as _mp_id,
    tt.sta_id as _sta_id,
    tt.tr_number_s as _tr_number_s,
    tt.tr_tstamp_ts as _tr_tstamp_ts,
    tt.tr_team_s as _tr_team_s,
    tt.tr_comment_s as _tr_comment_s,
    tt.kld_id_medium as _kld_id_medium,
    tt.kld_id_reason as _kld_id_reason,
    tt.kld_id_typeofsmpl as _kld_id_typeofsmpl,
    sp.sp_id as _sp_id,
    sa.sa_id as _sa_id,
    sa.sa_depth_fl as _sa_depth_fl,
    fr.fr_number_l as _fr_number_l,
    kd.kld_value_s as dataSource,
    case dataSource
        when 'Field' then 0
        when 'Unknown' then 0
        else 1
    end
from #temp_trace tt
    inner join spot sp on sp.tr_id = tt.tr_id
    inner join sample sa on sa.sp_id = sp.sp_id
    inner join fraction fr on fr.sa_id = sa.sa_id
    inner join kld_data kd on kd.kld_id = fr.kld_id_datasource
where mp_id = @tr_mp_id and
    sta_id = @tr_sta_id and
    CAST(tr_tstamp_ts as DATE) = CAST(@tr_tstamp_ts as DATE)

Answer 1

As far as I understand, dataSource is not a column name in any of your joining tables. It actually is an alias of kd.kld_value_s . You need to change your case like below:

case kd.kld_value_s
    when 'Field' then 0
    when 'Unknown' then 0
    else 1
end

Answer 2

try follwing. it may helps you

 CASE WHEN kd.kld_value_s = 'Field' THEN 0
      WHEN kd.kld_value_s = 'Unknown' THEN 0
      ELSE 1
 END AS dataSource