Someone

CREATE SQL VIEW v_ventas_reservas AS ;
SELECT vr.idventa, vr.tipodoc, c.nrocontrato+SPACE(3) AS nro, cli.nombre, cli.apellido ;
FROM ventas_reserva vr, contratos c, clientes cli ;
WHERE vr.tipodoc=="CONALM" AND vr.iddoc==c.idcontrato AND vr.idcliente==cli.idcliente ;
UNION ALL ;
SELECT vr.idventa, vr.tipodoc, c.nrocontrato+SPACE(3) AS nro ;
FROM ventas_reserva vr, contratos_avl c ;
WHERE vr.tipodoc=="CONAVL" AND vr.iddoc==c.idcontrato ;
UNION ALL ;
SELECT vr.idventa, vr.tipodoc, s.nro_solvta+SPACE(3) as nro ;
FROM ventas_reserva vr, solicitud_vta s ;
WHERE vr.tipodoc=="SOLVTA" AND vr.iddoc==s.idsolicvta ;
UNION ALL ;
SELECT vr.idventa, vr.tipodoc, a.nroanexo as nro ;
FROM ventas_reserva vr, anexos a ;
WHERE vr.tipodoc=="ANXALM" AND vr.iddoc==a.idanexo ;
UNION ALL ;
SELECT vr.idventa, vr.tipodoc, a.nroanexo as nro ;
FROM ventas_reserva vr, anexos_avl a ;
WHERE vr.tipodoc=="ANXAVL" AND vr.iddoc==a.idanexo ;
UNION ALL ;
SELECT vr.idventa, vr.tipodoc, STR(nroops, 8) as nro ;
FROM ventas_reserva vr, ops o ;
WHERE vr.tipodoc=="OPSALM" AND vr.iddoc==o.idops ;
UNION ALL ;
SELECT vr.idventa, vr.tipodoc, STR(nroops, 8) as nro ;
FROM ventas_reserva vr, ops o ;
WHERE vr.tipodoc=="OPSAVL" AND vr.iddoc==o.idops ;
UNION ALL ;
SELECT vr.idventa, vr.tipodoc, STR(nroops, 8) as nro ;
FROM ventas_reserva vr, ops o ;
WHERE vr.tipodoc=="OPSVTA" AND vr.iddoc==o.idops ;