[SQL] Inserting an IF statement in the middle of a SELECT in pl/pgSQL code

[Norm Garand]

Hi:

I can't seem to resolve this issue. I have a fair sized SELECT statement that 
runs properly in a
stored procedure using pl/pgSQL, but I have certain parts of the query that can 
filter by a NULL
value, or a character string.
What I can't seem to do is insert a conditional IF statement in my code.

Here is how it starts:

DECLARE
r zrec_dd_holder%rowtype;
BEGIN
FOR r IN 

SELECT DISTINCT(pi.serial_number) AS "Incident ID",
 to_char(pi.incident_date,'Mon-dd-yyyy') AS "Incident date",
 to_char(pi.date_created,'Mon-dd-yyyy') AS "Report Date",

 CASE  
  WHEN EXTRACT ( MONTH FROM pi.incident_date ) = 1 THEN 1 
  WHEN EXTRACT ( MONTH FROM pi.incident_date ) = 2 THEN 1 
  WHEN EXTRACT ( MONTH FROM pi.incident_date ) = 3 THEN 1
  WHEN EXTRACT ( MONTH FROM pi.incident_date ) = 4 THEN 2 
  WHEN EXTRACT ( MONTH FROM pi.incident_date ) = 5 THEN 2 
  WHEN EXTRACT ( MONTH FROM pi.incident_date ) = 6 THEN 2 
  WHEN EXTRACT ( MONTH FROM pi.incident_date ) = 7 THEN 3 
  WHEN EXTRACT ( MONTH FROM pi.incident_date ) = 8 THEN 3 
  WHEN EXTRACT ( MONTH FROM pi.incident_date ) = 9 THEN 3 
  WHEN EXTRACT ( MONTH FROM pi.incident_date ) = 10 THEN 4 
  WHEN EXTRACT ( MONTH FROM pi.incident_date ) = 11 THEN 4 
  WHEN EXTRACT ( MONTH FROM pi.incident_date ) = 12 THEN 4 
 END AS "Quarter",

 pf.name  AS "Facility",
 pl.name  AS "General Location",
 f.long_desc  AS "Specific Location", 
......

The user can choose to allow the default (in this case NULL) or supply a 
predetermined value for
"Specific Location".

In the WHERE portion of the SELECT statment, I'd like to insert the IF 
statement shown below. I've
tried single and double quotes and the pipeline for concatenation, but nothing 
seems to work. Any
suggestions or resolutions would be greatly appreciated. Please feel free to 
contact me directly.

AND pi.id = pid.id
 AND ( pid.incident_type_cid BETWEEN 117 AND 123 )

/--------------- 
 IF $7 IS NOT NULL THEN
  AND f.id = pid.specific_location_cid AND f.long_desc = $7 
 END IF
---------------/ 

 AND ( pi.location_id = pl.id )
 AND pf.id = pl.facility_id
 
 AND pi.person_status_code_id = b.id



regards,

Norm

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