sql - Oracle SQL 隐藏重复值

Question

我有一个关于这些结果的查询:

A | 1
A | 2
B | 1
B | 2
B | 3

如何得到这样的结果:

A | 1
  | 2  
B | 1   
  | 2   
  | 3

Answer 1

这是一种方法:

SELECT CASE WHEN rn = 1 THEN c1 ELSE NULL END || ' | ' || c2
  FROM (SELECT c1, c2, ROW_NUMBER() OVER (PARTITION BY c1 ORDER BY c2) rn
          FROM your_table);