In blockchain, data is only inserted at the end of previous data.
In traditional DBMS you can insert, update and delete data.
Then, in the blockchain, you can check any point in history. and it will not be altered.
Any new data that add to blockchain has at least 2 parts.
1.- The data itself
2.- a value that is a result of some kind of calculus on the previous record.
That doesn’t mean that data cannot change. If data change or not is your interpretation when you read it.
For example, you can have a blockchain database that registers how tall are you. Each day you are higher or lower you add data with your name, how tall are you, and the date and time you are registering.
Then you can check how tall were you at every moment. If you want to check how tall are you now, you will get the record with a later date.