按“IN”oracle 11g 中传递的值的顺序获取结果

Question

我有

SELECT * FROM adp_relations WHERE rel_name IN ('primary2bus_org', 'employee2user')

我想选择并返回具有我在 IN 子句中传递的指定顺序的记录（首先显示具有 primary2bus_org='xyz'、employee2user='abc'、...的记录）

这样做的有效方法是什么？

Answer 1

一种方法是使用派生表：

;WITH cte AS
(
  SELECT 'primary2bus_org' AS rel_name, 1 AS orderNum FROM dual
  UNION ALL
  SELECT 'employee2user' AS rel_name, 2 AS orderNum FROM dual
)
SELECT a.* 
FROM adp_relations a
JOIN cte c
  ON a.rel_name = c.rel_name
ORDER BY c.orderNum;

请注意，如果您的adp_relations 多次出现任何搜索字符串，则每个“子组”的顺序将是非确定性的（或者更确切地说取决于执行计划）：

1 primary2bus_org
2 primary2bus_org
3 primary2bus_org
10 employee2user

vs

3 primary2bus_org
2 primary2bus_org
1 primary2bus_org
10 employee2user

如果是这样，您应该添加ORDER BY c.orderNum, a.<col_which_is_unique_like_id> 以获得稳定的排序。