Bissiness logic is concept of n-tier coding. Create a class to connect Application layer and data layer.

in the business layer we write the bussiness related logic get the information from application layer and write the some logic in bussiness layer and pass to data layer.

Dl_DataLayer Dl_obj=new Dl_DataLayer

public void Getdata(Al_GetData  Al_Obj)

{

int age=AlObj.age;

if(age>25)

{

decimal height=5.5;

Dl_obj.GetData(height);

}

}