Selecting a single column in SQL

Question

Hi all,
I am doign a Java application at the moment and I need to select only a single column in a row of a table.
I know that I can do something like
SELECT column_name FROM table
but the fact is, I am not supposed to know the name of the column, but only its content. The row can be determined by a CUSTOMER_ID and in the row resulting from the SELECT, one of the column has "2" as content.
I would then like to know how I can build my query to only select this column, because I will then be able to retrieve the column name using the getColumnName() from the ResultSetMetadata.
I hope it was clearly said, thanks.
D.

Answer 1

OMG, that table isn't even in first normal form. Whoever designed the model for that application needs to get some training. If it were properly normalized, the problem would be simple, as it is you're in a mess (as I'm sure lots of code that tries to use that table is). If it were normalized, the query would look something like this ...
select status
from customer_transaction
where transaction_code = 2;Or even better, transaction code would be more meaningful and have a code table of it's own where you could refer to it with something less obscure than the number 2.
You could create a view that makes that table appear denormalized using 100 union alls but it wouldn't perform worth a damn. All I can think of is that you'll need to generate a query that looks something like this ...
select case when tan_1 = 2 then 'STATUS_TAN_1'
when tan_2 = 2 then 'STATUS_TAN_2'
when tan_3 = 2 then 'STATUS_TAN_3'
end
from tan ...Then you can build your dynamic update using that returned column name.