Lo acabo de realizar con un Stored Procedure :
Código SQL
[-]CREATE OR ALTER PROCEDURE PRUEBA (
in_Clave integer,
in_count integer)
returns (
out_B Char(1))
as
declare variable sel_B char(1);
declare variable aux_count integer;
begin
AUX_COUNT = 1;
OUT_B = null;
For Select CAMPO_1
from TABLA_B
where CLAVE1 = :IN_CLAVE
into SEL_B
do begin
if (:AUX_COUNT = :IN_COUNT) then begin
OUT_B = :SEL_B;
Suspend;
Leave;
end
AUX_COUNT = AUX_COUNT + 1;
end
end
Y la consulta sería algo como
Código SQL
[-]Select TA.CAMPO_1 TB.OUT_B
from TABLA_A TA
left join PRUEBA(TA.CLAVE1, CAMPO_1) TB
on TA.CAMPO_1 = TA.CAMPO_1