Baan 系统里写了一个SQL语句怎么也执行不出来，请大家看一下原因？谢谢

Baan 系统里写了一个SQL语句怎么也执行不出来，请大家看一下原因？

 

|******************************************************************************
|* tisqlpoccs1   VRC B40C c4 cus
|* PO CCS with invoice approval
|* mbywsun
|* 19-07-10 [13:00]
|******************************************************************************
declaration:
extern domain tcdate app.date

table ttdpur040
table ttdpur041
table ttdpur046

detail.1:
before.layout:
              select * from tdpur046

              where tdpur046.orno = :tdpur041.orno

                and tdpur046.pono = :tdpur041.pono

              selectdo
                          app.date = tdpur046.pdat
             
              selectempty
                          app.date = 0

              endselect