誤差變換數據類型爲varchar爲bigint使用聯合

Question

查詢：

SELECT TOP (1) '-1' AS hrempid, 'All employees' AS fullname 
FROM employee 
UNION 
SELECT fullname, hrempid 
FROM employee AS employee1 
order by fullname 

錯誤： 誤差變換數據類型爲varchar爲bigint。

Answer 1

您在union之後的順序錯誤。下面是修改後的版本：

SELECT TOP (1) '-1' AS hrempid, 'All employees' AS fullname 
FROM  employee 
UNION 
SELECT hrempid, fullname 
FROM  employee AS employee1 
ORDER BY fullname 

而且更好的是，使用這樣的：

SELECT CAST(-1 AS BIGINT) AS hrempid, 'All employees' AS fullname 
UNION ALL 
SELECT hrempid, fullname 
FROM  employee AS employee1 
ORDER BY fullname 

Answer 2

留下你hrempid圍繞'並切換列。試試這個：

SELECT TOP (1) 'All employees' AS fullname, -1 AS hrempid 
FROM employee 
UNION 
SELECT fullname, hrempid 
FROM employee AS employee1 
order by fullname