Question

我有一个大的存储过程，其中有一个子查询，如下所示。

SELECT COUNT(userID) AS totalLikes FROM apsLikes WHERE likeID = 'empowerment_'+A.[submissionID]
FOR    XML PATH ('likes'), TYPE, ELEMENTS

在likeID列中，我的值为prefix_id

当我尝试运行查询时出现此错误：

Conversion failed when converting the varchar value 'empowerment_' to data type int.

likeID的数据类型是varchar（60），所以不确定它是什么意思？

Answer 1

只需做一个明确的cast()：

SELECT COUNT(userID) AS totalLikes
FROM apsLikes
WHERE likeID = 'empowerment_' + cast(A.[submissionID] as varchar(255))
FOR    XML PATH ('likes'), TYPE, ELEMENTS;

问题是+可能意味着添加或字符串连接。因为第二个参数是整数，所以它假定+是加法，并且'empowerment_'不能转换为整数。因此，错误。

Answer 2

SubmissionID可能是数据typeint。试试这个。

SELECT COUNT(userID) AS totalLikes 
FROM apsLikes WHERE likeID = 'empowerment_'+ CAST(A.[submissionID] AS NVARCHAR(255))
FOR    XML PATH ('likes'), TYPE, ELEMENTS

Answer 3

问题是SQL Server将加号解释为加法运算符而不是连接运算符。试试这个：

SELECT COUNT(userID) AS totalLikes 
FROM apsLikes WHERE likeID = 'empowerment_'+ CAST(A.[submissionID] AS VARCHAR(50))
FOR XML PATH ('likes'), TYPE, ELEMENTS

带有列前缀的SQL子查询

3 个答案: