How to check that all information from one database is transferred to another?

Question

1C

There is an outdated database architecture that has been in use for 20 years and has not been updated. The management ordered a full migration for 1s, with a completely different data structure (information will be merged from several old tables into one new one, etc.)
How can you verify that all data has been transferred as reliably as possible? Maybe Sum(total), count(Total)? What about non-numeric fields?

Answer 1

Check numerical indicators by amount, and quantitative indicators by quantity. Make a data migration plan considering the relationships between the data. Record benchmarks at the start. For example, for accounts - their number and amount, you can also do this with a breakdown by counterparties. Pay attention to the relevance of this data. Surely there is something that is not needed now with high detail. Those. Some data can be turned around.
Total - business data requirements and benchmarks.
Good luck.

Answer 2

There was a question of acceptance of information transfer.

They prepare Excel, you load it. Especially the new structure.
And so you sit down with the customer (management) and ask him this question. You must collectively decide the points of verification, incl. it is advisable to fix this on paper when they start turning on the return line.
To push that the check was not carried out by the one who endures.

Answer 3

I so understood the main question in not numerical fields.
If you are sure that in DB1.table1 there must be exactly the same set of values ​​as in DB2.table2, then you have at least two options:
use a hash function or CRC - these are special functions that count a certain number for any data. And if the data differs even by a letter, then with a very high probability the hash / crc will also differ.
Since you have 1c on one side of the comparison, I assume that you have it in MS SQL, here is a link to such functions in it. Then it remains to find a similar function in the source database.
https://docs.microsoft.com/en-us/sql/t-sql/functio...