sql - 如何在 SQL 语句语法中执行内联 if-then

Question

我正在尝试将我的电子邮件附加到我的@email 字符串中，传入了错误的@status。它可以在没有我注释掉的行的情况下工作。我想我很接近，但语法错误。@override_email 为空。

DECLARE @retval INT
DECLARE @email nvarchar(200)
DECLARE @override_email nvarchar(200) = null
DECLARE @status INT = 2
DECLARE @in_customer_id INT = 160308

SET @email = COALESCE(@override_email, (
                      SELECT
                        COALESCE(CustomerDetail.Email, '')
                        /*+ (if @status NOT IN (3,4,5) ', alex@email.com')*/
                      FROM
                        tbl_customer_detail     CustomerDetail
                      WHERE
                        CustomerDetail.customer_id = @in_customer_id))                      
select @email

Answer 1

您可以使用CASE表达式执行此操作：

DECLARE @retval INT
DECLARE @email nvarchar(200)
DECLARE @override_email nvarchar(200) = null
DECLARE @status INT = 2
DECLARE @in_customer_id INT = 160308

SET @email = COALESCE(@override_email, (
                      SELECT
                        COALESCE(CustomerDetail.Email, '')
                        + case when @status NOT IN (3,4,5) then ', alex@email.com' else '' end
                      FROM
                        tbl_customer_detail     CustomerDetail
                      WHERE
                        CustomerDetail.customer_id = @in_customer_id))                      
select @email