Can we create a decision table in Appian? If yes, can it pretty generic or we ha

There is a Decision Table Shared Component that is available that might meet your needs - or at least give you a starting point.
forum.appian.com/.../summary

This isn't available natively but if you search in Shared Components you'll find a plugin application that might well meet your requirements.

Thanks Christineh & Tim

Actually, what I want is a grid where each field is in one column. We can add the add more columns in grid or take out columns in grid to add more conditions. The elements in each row are having an intersection relationship only if the element is present for that field. As the end result of that relationship we can set the value. For example, we have field1, field 2 & field3. They have value1, value2 & value 3 respectively. If the "AND" relationship is true between them, we get result1 as value. If not, it checks next condition, where only field1 & field 2have values as value1 & value2. Field 3 is blank. Now it will check condition for calu1 and value 2 only for "And" & will give the result as result2.