在SQL Server中将NULL转换为空字符串

Question

我为'AltReimMethod'获取Null值，我想将其转换为空字符串值。这是查询：

(SELECT rc.name from ReimbursementChoice rc WHERE rc.admin_id = a.admin_id AND rc.choice_id = pe.alt_payment_choice) AS 'AltReimMethod'

我试过

(SELECT (ISNULL(rc.name,' ')) from ReimbursementChoice rc WHERE rc.admin_id = a.admin_id AND rc.choice_id = pe.alt_payment_choice) AS 'AltReimMethod'

还

(SELECT (ISNULL(CONVERT(varchar(50),rc.name),' ')) from ReimbursementChoice rc WHERE rc.admin_id = a.admin_id AND rc.choice_id = pe.alt_payment_choice) AS 'AltReimMethod'

他们没有显示任何错误，但我甚至没有得到任何结果。

Answer 1

在查询时应用IsNull，而不是在查询中应用isnull：

ISNULL((SELECT rc.name from ReimbursementChoice rc WHERE 
rc.admin_id = a.admin_id AND rc.choice_id = pe.alt_payment_choice),' ') 
AS 'AltReimMethod'