Question

我对SQL查询不是很熟悉。最近我尝试使用SQL Server的unpivot功能构建查询，但我遇到的错误是：

列“U_ItemModality”的类型与其他类型冲突 UNPIVOT列表中指定的列。

这是我的问题：

select 
    cast(unpvt.ItemCode collate database_default AS VARCHAR(30)) as ItemCode,
    cast(unpvt.attribute collate database_default AS VARCHAR(30)) as attribute,
    cast(unpvt.value collate database_default AS VARCHAR(30)) as value 
from [OITM]
unpivot (
    value for attribute in (U_Mfg_Part_Num, U_Part_Descriptor, U_ItemModality)
) unpvt
inner join [@AECTRANDATA] as WI 
    on unpvt.ItemCode = WI.U_ObjectKeyValue
inner join OITM AS IM 
    on WI.U_ObjectKeyValue = IM.ItemCode 
where 
    WI.U_ObjectType ='4'

在此查询中，如果我删除u_itemmodality，它将会运行。其他两列的大小为100字符，但此列的大小为30字符。

如何克服这种情况？

Answer 1

使用UNPIVOT时，数据类型的长度必须相等。有关详细信息，请参阅此question。您应该将U_ItemModality转换为VARCHAR(100)，以使其与其他两列的长度相同。

select 
    cast(unpvt.ItemCode collate database_default AS VARCHAR(30)) as ItemCode,
    cast(unpvt.attribute collate database_default AS VARCHAR(30)) as attribute,
    cast(unpvt.value collate database_default AS VARCHAR(30)) as value 
from (
    select
        U_Mfg_Part_Num,
        U_Part_Descriptor,
        U_ItemModality = convert(varchar(100), U_ItemModality)
    from [OITM]
)t
unpivot (
    value for attribute in (U_Mfg_Part_Num, U_Part_Descriptor, U_ItemModality)
) unpvt
inner join [@AECTRANDATA] as WI 
    on unpvt.ItemCode = WI.U_ObjectKeyValue
inner join OITM AS IM 
    on WI.U_ObjectKeyValue = IM.ItemCode 
where 
    WI.U_ObjectType ='4'

面对SQL Unpivot查询中列数据类型的困难

1 个答案: