Row_Number（）继续在Union all查询中

Question

如果我有3张桌子，如何获得增量唯一编号？

例如：

• 第一个查询row_number result = 1,2,3
• 第二个查询row_number结果= 4,5,6
• 第3次查询row_number result = 7,8,9

我尝试了以下查询，但从中我可以获得增量到第二个表。

SELECT ROW_NUMBER() OVER(ORDER BY filename) AS SrNo,fileName FROM Tab1
UNION ALL
SELECT ROW_NUMBER() OVER(ORDER BY filename) + (SELECT COUNT(*) FROM tab1) AS 
SrNo, filename FROM Tab2
UNION ALL
SELECT ROW_NUMBER() OVER(ORDER BY filename) + (SELECT COUNT(*) FROM tab2) AS 
SrNo, filename FROM Tab3

每个表有3条记录，我想得到row_number的结果为1,2,3,4,5,6,7,8,9

Answer 1

使用子查询：

SELECT ROW_NUMBER() OVER (ORDER BY which, filename) as SrNo, filename
FROM (SELECT 1 as which, fileName FROM Tab1
      UNION ALL
      SELECT 2 as which, filename FROM Tab2
      UNION ALL
      SELECT 3 as which, filename FROM Tab3
     ) ttt;