Error : The type of column "DOB" conflicts with the type of other columns specified in the UNPIVOT list

Question

我的查询，

只是把行转成列

SELECT
  ColumnName,
  value
FROM (SELECT
  id [ID],
  firstname [First Name],
  lastname [Last Name],
  dob [DOB],
  sex [Gender]
FROM client
WHERE id = '11') d
UNPIVOT
(
Value FOR
ColumnName IN ([ID], [First Name], [Last Name], [DOB], [Gender])
) unpiv;

但是显示错误。

The type of column "DOB" conflicts with the type of other columns specified in the UNPIVOT list.

Answer 1

由于结果将返回行中的所有列，构建包含所有值的新派生列，因此您必须确保类型适合。

您可以将所有列包装在 CAST

中

SELECT
  ColumnName,
  value
FROM (SELECT
  CAST(id AS NVARCHAR(MAX)) [ID],
  CAST(firstname AS NVARCHAR(MAX)) [First Name],
  CAST(lastname AS NVARCHAR(MAX)) [Last Name],
  CAST(dob AS NVARCHAR(MAX)) [DOB],
  CAST(sex AS NVARCHAR(MAX)) [Gender]
FROM client
WHERE id = '11') d
UNPIVOT
(
Value FOR
ColumnName IN ([ID], [First Name], [Last Name], [DOB], [Gender])
) unpiv;

DOB 将转换为您机器的默认设置。使用 CONVERT 您可以强制执行给定的 date/time 格式。