with PSQLQuery1 do
    begin
      Filtered:=false;
      Filter:= 'name LIKE '''+Edit1.text+'%''';
      Filtered:=true;
    end;

SELECT  name::varchar( 100 ) from person;

SELECT  name::varchar( 100 ) from organization;

SELECT   name::varchar( 100 ) from person
UNION
SELECT   name::varchar( 100 ) from organization;

SELECT c.id_contractor,
       CASE WHEN (c.id_contractor_type= 16 ) OR (id_contractor_type= 17 ) THEN p.name 
       ELSE o.name END
FROM contractor c
LEFT JOIN person p
ON c.id_contractor=p.id_contractor
LEFT JOIN organization o
ON c.id_contractor=o.id_contractor