Question

我需要在select语句中添加新列，其中包含所有记录中的最大年份（存储为文本），然后将其标记为CY / PY。桌子上总是只有两年。

 year    value   
 2019    value1  
 2019    value2  
 2018    value3

到目前为止，我已经尝试过了，但是它只返回那一行的max，而不是整列。

 select year, value, IIF(year=MAX(year), 'CY', 'PY') AS "CY/PY" from table

预期：

year    value     CY/PY
2019    value1    CY
2019    value2    CY
2018    value3    PY

Answer 1

我认为您想要一个窗口函数：

select year, value,
       (case when year = MAX(year) over () then 'CY' else 'PY' end) AS "CY/PY"
from table

Answer 2

尝试将MAX用作分析函数：

WITH cte AS (
    SELECT year, value, MAX(year) OVER () AS max_year
    FROM yourTable
)

SELECT
    year,
    value,
    IIF(year = max_year, 'CY', 'PY') AS "CY/PY"
FROM cte;

Answer 3

尝试在IIF中使用子查询：

select year, value, IIF(year=(select MAX(year) from table), 'CY', 'PY') AS "CY/PY" from table

列中所有值到新列的最大值

3 个答案: