Обсуждение: case statement to cath nulls on joined tables

Hello,

I am doing a left outer join between a polygon table and a data table.

 Everything

returns fine from this join as expected.  However, there are cases where

there isn?t data for a given polygon and this return as the expected null

in the result set.  I would like to utilize something like a case statement

to catch the nulls and return a ?more friendly? message.  I have tried

unsuccessfully to use the following logic:

*Select case value_of_interest null then ?more friendly message? else

value_of_interest end*

*From poly_table left outer join data_table one poly_table.common_id =

data_table.common_id*

If someone could let me know where I am going wrong it would be greatly

appreciated.

Cheers,

Derek

Try that:

SELECT address, CASE WHEN value_of_interest IS NULL THEN 'more friendly message' ELSE value_of_interest END value_of_interest

From poly_table left outer join data_table one poly_table.common_id = data_table.common_id

--
Matheus de Oliveira

On Fri, Feb 3, 2012 at 10:45 AM, John Morgan <jdmorgan@unca.edu> wrote:

Hello,

I am doing a left outer join between a polygon table and a data table.

 Everything

returns fine from this join as expected.  However, there are cases where

there isn?t data for a given polygon and this return as the expected null

in the result set.  I would like to utilize something like a case statement

to catch the nulls and return a ?more friendly? message.  I have tried

unsuccessfully to use the following logic:

*Select case value_of_interest null then ?more friendly message? else

value_of_interest end*

*From poly_table left outer join data_table one poly_table.common_id =

data_table.common_id*

If someone could let me know where I am going wrong it would be greatly

appreciated.

Cheers,

Derek