Sorry,I'm useing a traditional Chinese system,so I write my question in Engish.
First,I really thank a friend named billie for his answer,however I still can't solve my question.The help text for TField.CustomConstraint says a
sentence x>0 and x<10 ,I don't understand what the 'x' refer to and how to use the property in program. Who can tell me? By the way,I'm interested in programming and using Delphi now.You can contact me.