When I creat a dynamic DB contains a Dynamic tables, when the table changed, I mean when its field become less or more dynamically, how it will maintain its data, for example if I reduced the field, that's to say I altered the table by deleting 1 field, the old data that this field had it before how to maintain it and in which way, please guide and I appreciate any help, thank u all.
If you remove a column from a table, that data is not maintained in any way. It's gone. Period. There is not automatic method that protects against someone with Data Definition Language access to the server shortening a data type in a column or anything else. Any sort of alterations along these lines will lead to data loss. What is it that you're trying to do that you would both want to retain data and drop the columns that the data is stored in?