Thank you Mr ofer .
actually I have already tried this but getting wrong results.
I am trying to creat a query with multi criteria : patient name , hospital
etc.
for the patient name it is working ok , because each record must have a
patient name (the field "Patient" in each record is not blank)
but for the field Hospital , some records have this field null (blank) that
is why the result coming is wrong , I have 1865 records , out of them there
are only 792 records with the Hospital name entered .so , when i use this
expression I get only 792 although the total records are 1865.
how can I solve this.