mysql - 使用 UNION 从多个表中选择

Question

我尝试使用 UNION 从一个数据库的 3 个表中选择记录，但出现错误:

#1248 - Every derived table must have its own alias

这是我正在尝试的查询:

SELECT * from
  (SELECT column1, 'table1' from table1
UNION
   SELECT column1, 'table2'  from table2
UNION
   SELECT column1, 'table3'  from table3) 
WHERE column1 not like 'abr%' and length(column1) < 8;

该错误的确切含义是什么？我该如何修复它并显示正确的结果？

Answer 1

SELECT Alis.column1 
  FROM (SELECT column1, 'table1' as which from table1
  UNION ALL
      SELECT column1, 'table2' from table2
  UNION ALL
      SELECT column1, 'table3' from table3
 ) Alis
WHERE column1 not like 'abr%' and length(column1) < 8;