文本、ntext 和图像数据 >类型不能比较或排序，除非使用 IS NULL 或 LIKE >操作员 [英] The text, ntext, and image data > types cannot be compared or sorted, except when using IS NULL or LIKE > operator

问题描述

电子邮件属于预订表，在我们的 Microsoft sql 服务器中定义为文本"类型

email belongs to table booking and its defined as type "Text" in our Microsoft sql server

SELECT email, 
 COUNT(email) AS NumOccurrences
FROM Booking
GROUP BY email
HAVING ( COUNT(email) > 1 )

运行上述查询后(尝试在预订中查找重复的电子邮件)我收到如下错误消息:

after running the above query(trying to find duplicates emails in the booking) I got the error message like this:

text、ntext 和 image 数据类型不能比较或排序，除非使用 IS NULL 或 LIKE操作员.

The text, ntext, and image data types cannot be compared or sorted, except when using IS NULL or LIKE operator.

我正在使用 Microsoft Sql

I am using Microsoft Sql

推荐答案

既然你用的是SQL Server，为什么不把数据类型改成VARCHAR(100)?

since you are using SQL Server, why not change the data type to VARCHAR(100)?

要在不更改数据类型的情况下解决此错误，在 ORDER BY 中使用时，TEXT 或 NTEXT 列需要转换为 VARCHAR 或 NVARCHAR 子句或 SELECT 语句的 GROUP BY 子句.例如，有点乱

To work around this error without changing the datatype, the TEXT or NTEXT column needs to be converted to VARCHAR or NVARCHAR when used in either the ORDER BY clause or the GROUP BY clause of a SELECT statement. eg, which is alittle bit messy

SELECT  CAST(email AS NVARCHAR(100)) email, 
        COUNT(CAST(email AS NVARCHAR(100))) AS NumOccurrences
FROM    Booking
GROUP   BY CAST(email AS NVARCHAR(100))
HAVING  COUNT(CAST(email AS NVARCHAR(100))) > 1 

• SQL Server 错误消息 - 消息 306

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