Question

以下查询给出错误：

SELECT DISTINCT dealer_state
FROM A
WHERE country='SS' 
UNION
SELECT DISTINCT dealer_state
FROM B
WHERE country='SS'
ORDER BY upper(dealer_state)

如何按顺序使用upper（列）进行排序？

Answer 1

假设您的查询给出的“错误”是它没有按照您的预期从B的记录中排序来自A的记录，您需要将UNION查询设为子查询到执行排序的那个：

SELECT dealer_state FROM (
    SELECT dealer_state FROM A WHERE country='SS' 
  UNION
    SELECT dealer_state FROM B WHERE country='SS'
) t
ORDER BY upper(dealer_state)

Answer 2

DISTINCT和ORDER BY中最左边的表达式必须匹配。

最简单的方法是执行以下操作：

SELECT dds FROM (
    SELECT DISTINCT dealer_state AS dds FROM A
     WHERE country='SS'
    UNION
    SELECT DISTINCT dealer_state AS dds FROM B
     WHERE country='SS') AS d
ORDER BY upper(dds);

当我们需要使用upper（列名）进行排序时，如何在oracle中使用带有union子句的order by子句？

2 个答案: