How to return 1 single row data from 2 different t

问题:

Can someone provide answer to this situation?? Suppose I have 2 tables:

Table Books with values Batch_no and Title

Batch_no - Title
1 - A
2 - B

and;

Table Book_Authors with values Batch_no and Author_no

Batch_no - Author_no
1 - 1
1 - 2
1 - 3
2 - 1

How should I merge the values into 1 row which should look like this

Batch_no Author
1 - 1, 2, 3
2 - 1

Any help will be greatly appreciated...Many Thanks!

回答1:

If you take a look here: http://www.simple-talk.com/sql/t-sql-programming/concatenating-row-values-in-transact-sql/

there are several techniques you can do this.

Adapting for your situation, here is one that looks simple:

    select batch_no, LEFT(booksauthors, len(booksauthors)-1) as Authors from 
(SELECT ba.Batch_no,

      ( SELECT cast(ba1.Author_no as varchar(10)) + ','

           FROM Book_Authors ba1

          WHERE ba1.Batch_no = ba.Batch_no

          ORDER BY Author_no

            FOR XML PATH('') ) AS BooksAuthors

      FROM Book_Authors ba

      GROUP BY Batch_no )A;