有时您希望将字符串或 int 附加到给定列中的数据,例如SELECT 1005 + ID FROM Users
(您将在 ID 列数据中添加 1005)。对于动态创建的列,如何做到这一点?
以下作品:
SELECT ID,
Name,
(SELECT Email FROM Emails WHERE Emails.ID = d.ID) AS Email,
Address
FROM data d
但是添加以下新行会产生错误Invalid column name "Email"
:
SELECT ID,
Name,
(SELECT Email FROM Emails WHERE Emails.ID = d.ID) AS Email,
Email + ' testing ' AS Test, /* New line that causes error */
Address
FROM data d
如何修复此错误?