sql - 此处如何使用案例

Question

我需要创建一个 SQL 查询来从数据库生成以下输出。

我正在搜索这样的条件

When week_val is 1 then hour_val should come from week_val 2 row. Otherwise hour_val comes from same row.

Answer 1

SELECT week_val, (CASE week_val 
  WHEN 1 THEN (SELECT hour_val FROM your_tbl WHERE week_val = 2) 
  ELSE hour_val) 
FROM your_tbl;