使用Java合并两个ms访问数据库

Question

I am trying to merge two database of ms access using Java . I am making connection from one database and and another connection from other database. I am copying all records from each table to the tables in the another database.

Is there any other solution rather than copying records from one database tables to another database tables. both database have the same table structure.

Answer 1

For the most part, there is a lot more to copying a relational database than simply copying the tables. For example, you must consider the order the data is copied to avoid violating integrity.

Regarding the SQL for copying, Access will accept the name of an external mdb / acdb as a detination, so the first two statements will work as long as you have no attachment or multi-value field data types. Another problem is autonumber IDs, if they are likely to overlap, INSERT INTO is unsafe as you may end up with duplicates.

SELECT * INTO AnotherTest IN 'Z:\Docs\test.accdb'
FROM test;

INSERT INTO AnotherTest IN 'Z:\Docs\test.accdb'
SELECT  *
FROM test;

While the above INSERT will often work, it is much safer to list the fields, omitting any autonumber fields.

INSERT INTO AnotherTest ( AText, ADate, ANumber ) IN 'Z:\Docs\test.accdb'
SELECT test.AText, test.ADate, test.ANumber
FROM test;

All the statements were built using MS Access query design window and only slightly modified.

Answer 2

Are you using SQL to do this? If so it is probably a question of your SQL code rather then your java code.
You could multi-thread your program so that each table or set of tables is copied in a different thread. This is especially useful if the table names don't change as you could create an array of the table names and a thread sub-class that puts the names in your SQL query. If you used a thread pool of 10 or so threads this should speed it up, although be careful with this as my experience with access and java is that the database can corrupt very easily so make sure you have a backup before trying this.