Postgresql 如何列出两列串联的双条目？

如何列出两列串联的双条目

目前，我使用此查询在一列中列出双精度：

SELECT
    COUNT(col_a) AS count,
    col_a
FROM mytable
GROUP BY col_a
HAVING COUNT(col_a) > 1
ORDER BY count DESC

首先连接它们，然后执行操作：

SELECT
    COUNT(concat) AS count,
    concat
FROM (
    SELECT col_a || col_b AS concat FROM t
) s
GROUP BY concat
HAVING COUNT(concat) > 1
ORDER BY count DESC

---

将

col_a

替换为

col_a | | col_b

？@laurenzal如果它工作正常，谢谢！