错误而使用GROUP BY子句

Question

我收到SQL Server错误“一文ntext和image数据类型不能比较或排序，但使用时为空或像”在执行

SELECT r.Shift, l.lab_title AS [Assigned Lab], u.user_name AS [L/A], 
     CONVERT(varchar(100), t.Time) + ' To ' + CONVERT(varchar(100), h.Time) AS Timing 
    FROM table_roaster_time_table AS r 
     INNER JOIN table_time AS t ON r.timeId = t.timeId AND r.timeId = t.timeId 
     INNER JOIN table_user AS u ON r.user_id = u.user_id 
     INNER JOIN table_labs AS l ON r.lab_id = l.lab_id 
     INNER JOIN table_time2 AS h ON r.timeId2 = h.timeId2 
GROUP BY r.Shift, l.lab_title, u.user_name 

不要知道什么是问题。我也使用聚合函数，只是为了形式化，但它不起作用。

Answer 1

我猜你的r.Shift列是text或ntext类型。因此，它不能用于group by

一个选项可能是在可疑列上使用CAST，但可能会丢失数据。例如：

SELECT  r.Shift, l.lab_title AS [Assigned Lab], u.user_name AS [L/A], CONVERT(varchar(100),  t.Time) + ' To ' + CONVERT(varchar(100), h.Time) AS Timing 
FROM   table_roaster_time_table AS r INNER JOIN 
        table_time AS t ON r.timeId = t.timeId AND r.timeId = t.timeId INNER JOIN 
        table_user AS u ON r.user_id = u.user_id INNER JOIN 
        table_labs AS l ON r.lab_id = l.lab_id INNER JOIN 
        table_time2 AS h ON r.timeId2 = h.timeId2 
GROUP BY CAST(r.Shift as varchar(max), l.lab_title, u.user_name 

你也可以看看查询数据，而不text列，然后做第二查询来获取缺少的列。例如：

with temp as 
(
    SELECT  l.lab_title AS [Assigned Lab], u.user_name AS [L/A], CONVERT(varchar(100),  t.Time) + ' To ' + CONVERT(varchar(100), h.Time) AS Timing 
    FROM   table_roaster_time_table AS r INNER JOIN 
         table_time AS t ON r.timeId = t.timeId AND r.timeId = t.timeId INNER JOIN 
         table_user AS u ON r.user_id = u.user_id INNER JOIN 
         table_labs AS l ON r.lab_id = l.lab_id INNER JOIN 
         table_time2 AS h ON r.timeId2 = h.timeId2 
    GROUP BY l.lab_title, u.user_name 
) 
SELECT r.Shift, t.lab_title AS [Assigned Lab], t.user_name AS [L/A] --etc 
FROM   table_roaster_time_table AS r 
INNER JOIN temp as t 
on r.id = t.id --or whatver 

此外，该SQL似乎没有必要：

r.timeId = t.timeId AND r.timeId = t.timeId