Question

这是mi查询

with r as (
 select id, created_at from table1 ta 
)
select * from r 
union all 
select id, created_at  from table2 tb where confirmed_at IS null ORDER BY id DESC LIMIT 1
and not exists (
select * from r
)

，响应为 SQL错误[42804]：错误：AND的参数必须为布尔型，而不是整数位置：203

Answer 1

似乎仅在前半部分为空的情况下才想从联合的后半部分返回记录。这是一种方法：

WITH r AS (
    SELECT id, created_at FROM table1
)

SELECT id, created_at FROM r
UNION ALL
SELECT id, created_at
FROM table2
WHERE confirmed_at IS NULL AND (SELECT COUNT(*) FROM r) = 0
ORDER BY id DESC
LIMIT 1;

AND的参数必须为布尔型，而不是整数

1 个答案: