除了在ref_types表中具有ReferenceType列之外，您还需要一个Reference_ID列，该列将相应表中的实际ID引用为

In addition to having ReferenceType column in ref_types table, you also need a Reference_ID column that refers to the actual ID in the corresponding table as a foreign key.

//ref_types table
ID Article_ID ReferenceType Reference_ID
1  1          book          1
2  1          article       1
3  1          article       2
4  1          book          2

然后，您可以避免WHILE循环，而让MySQL通过JOIN为您完成工作:

Then, you can avoid a WHILE loop and let MySQL do the work for you with JOINs:

SELECT CONCAT('record ', rt.ID, ': ',
  COALESCE(ar.Article_Title, tr.Thesis_Title, br.Book_Title))
FROM ref_types rt
LEFT JOIN article_refs ar
  ON rt.ReferenceType = 'article' AND ar.ID = rt.Reference_ID
LEFT JOIN book_refs br
  ON rt.ReferenceType = 'book' AND br.ID = rt.Reference_ID
LEFT JOIN thesis_refs tr 
  ON rt.ReferenceType = 'thesis' AND tr.ID = rt.Reference_ID

得出结果:

record 1: book1
record 2: article1
record 3: article2
record 4: book2