SELECT * FROM documents WHERE id IN (5,3,6,1) ORDER BY FIELD(id,5,3,6,1);
或者
SELECT * FROM documents WHERE id IN (5,3,6,1) ORDER BY substring_index((id,5,3,6,1),id,1);
SELECT * FROM documents WHERE id IN (5,3,6,1) ORDER BY FIELD(id,5,3,6,1);
或者
SELECT * FROM documents WHERE id IN (5,3,6,1) ORDER BY substring_index((id,5,3,6,1),id,1);