有没有办法为 SQL 返回一个值而不是空白？

Question

我正在尝试做一个 HTML 表格，但我遇到了它不返回值的问题。 这个例子显示了我的结果。

是否可以编写脚本，如果没有任何结果，它将返回 0？ 我尝试了 ISNULL 方法，但它没有返回任何值。

我期待通过使用 ISNULL 方法，它会在结果中返回一个 0，但它并没有这样做。

    Select ISNULL(body,0) from [EMAIL_MATRIX] 
where body NOT IN(
SELECT c.Body
FROM [dbo].[EMAIL_DETAILS] a
INNER JOIN [Email_matrix] c 
ON SUBSTRING(a.Subject,5,LEN(a.Subject)-4) = c.Subject
 and a.Body LIKE CONCAT('%', c.body, '%') 
where Cast(a.Send as DAte) = '2022-10-04')

Answer 1

试试这个，

Select REPLACE(ISNULL(body,0),'',0) from [EMAIL_MATRIX] 
where body NOT IN(
SELECT c.Body
FROM [dbo].[EMAIL_DETAILS] a
INNER JOIN [Email_matrix] c 
ON SUBSTRING(a.Subject,5,LEN(a.Subject)-4) = c.Subject
 and a.Body LIKE CONCAT('%', c.body, '%') 
where Cast(a.Send as DAte) = '2022-10-04')

Answer 2

试试这个：

WITH DataSource AS
(
    Select ISNULL(body,0) AS body
    from [EMAIL_MATRIX] 
    where body NOT IN
    (
        SELECT c.Body
        FROM [dbo].[EMAIL_DETAILS] a
        INNER JOIN [Email_matrix] c 
            ON SUBSTRING(a.Subject,5,LEN(a.Subject)-4) = c.Subject
            and a.Body LIKE CONCAT('%', c.body, '%') 
        where Cast(a.Send as DAte) = '2022-10-04'
    )
)
SELECT body
FROM DataSource
WHERE EXISTS(SELECT 1 FROM DataSource)
UNION ALL
SELECT NULL
WHERE NOT EXISTS(SELECT 1 FROM DataSource)