[SQL] query configuration for validate empty quote to zero

[Yudie]

We just changed the postgresql server and got some problem with sql command in our old server we can exexute this query:   SELECT * FROM product WHERE prdtnumber = ''   field prdtnumber data type is integer and the empty quote somehow can be assumed into 0 (zero) Now,  if I use the same query it return an error: invalid input syntax for integer: ""   Anyone know what's the problem??   Thanks   Yudie