Re: SQL works but same function is confused

On 04/01/2014 06:10 PM, Bui, Michelle P wrote:
>
> Hi all,
>
> I have this query that when executed as a SQL statement, it works
> perfect! The table tools contains many records in a time series, with
> attributes like category but without the field status. I assign the
> value of status 'active' or 'inactive' depending on whether the tool
> record exists after a certain time (number of seconds).
>
> /SELECT category, v_status as status, count (tool_id) AS tool_count/
>
> /FROM /
>
> / (SELECT distinct category, tool_id, 'active' as v_status/
>
> / FROM tools/
>
> / WHERE time >= 123456/
>
> / UNION/
>
> / SELECT distinct e1.category, e1.tool_id, 'inactive'
> as v_status/
>
> / FROM tools e1/
>
> / WHERE not exists/
>
> / (SELECT e2.category, e2.tool_id/
>
> / FROM tools e2/
>
> / WHERE e2.sim_time >= 123456/
>
> / AND e2.category = e1.category/
>
> / AND e2.tool_id = e1.tool_id)/
>
> / ) AS derived_table/
>
> /GROUP BY category, Status/
>
> However, when I write a function to return the same result, using this
> SQL statement, and I declare a local variable v_status TEXT; it errors
> out when executed. The key complaint is:
>
> ERROR: column reference "v_status" is ambiguous...
>
> DETAIL: It could refer to either a PL/pgSQL variable or a table column.
>
> The function returns table (category, status, and tool_count) using
> RETURN QUERY in front of the query.
>
> I used <<block>> before Declare section and try using block.v_status
> but this is not allowed (has syntax error). When I use
> #variable_conflict use_variable, there is no error anymore, but the
> resulted Status field is null. Seemed like Postgresql does not assign
> the v_status as we wish.
>
> /CREATE OR REPLACE FUNCTION get_status/
>
> /RETURNS TABLE (category SMALLINT, status TEXT, tool_count BIGINT) AS/
>
> /$BODY$/
>
> //
>
> #variable_conflict use_variable
>
> /DECLARE/
>
> /v_status TEXT;/
>
> /BEGIN/
>
> / RETURN QUERY SELECT category, v_status as status, count (tool_id)
> AS tool_count/
>
> / FROM /
>
> / (SELECT distinct category, tool_id, 'active' as v_status/
>
> /FROM tools/
>
> / WHERE time >= 123456/
>
> / UNION/
>
> / SELECT distinct e1.category, e1.tool_id, 'inactive'
> as v_status/
>
> / FROM tools e1/
>
> / WHERE not exists/
>
> / (SELECT e2.category, e2.tool_id/
>
> / FROM tools e2/
>
> / WHERE e2.sim_time >= 123456/
>
> / AND e2.category = e1.category/
>
> / AND e2.tool_id = e1.tool_id)/
>
> / ) AS derivedTable/
>
> /GROUP BY category, Status;/
>
> //
>
> /END; $BODY$/
>
> /LANGUAGE plpgsql;/
>
> Thanks in advance for your insight or suggestion!
>
> Michelle
>

Then again, do you use "v_status" as a variable? select into v_status....