如何在没有联接的情况下查询多个相关表，并使用JDBC获得一致的数据？

Question

I am creating a process that connects to a given SQL Server database via JDBC, scans every table, and reads any new data that has been inserted or updated since the last run of this process. The owner of the database will not allow this process to do joins on any of the tables due to performance concerns.

The scenario in question

• Table A is a parent of table B
• This process reads data from Table A
• Prior to the process reading Table B, a new parent record is inserted into Table A and new child records are inserted into Table B
• When Table B is read, there will be child records present that don't have a corresponding parent record in the result set from the previous read of Table A

How can I query multiple related tables, without a join, and get consistent data using JDBC?

Answer 1

If you cannot do JOINs, you probably then just have to keep track of each retrieved primary key of each parent table and then use those for querying the child rows. It will complexify the queries, and add more strain to the DB, as you're executing more queries vs doing it in a single JOINed query, but it should give the same results.