Sql server 在SQL Server 2012中将varchar转换为float时出错

我已将一个大型Excel电子表格导入SQL Server数据库，默认情况下，所有列都是varchar数据类型。我的列sale列中也有空值。我想选择销售量作为双浮点数，它是varchar格式

我的查询如下，但我仍然得到一个转换错误

SELECT
    [CompanyCode] AS 'Company Code',
    [Sitecode] AS 'Site Code',
    [Product] AS 'Product Name',
    '' AS 'Tank ID',
    CONVERT(DATE, [InvDay]) AS Date,
    CAST([Sales] AS DECIMAL) AS 'Sale Volume',
    '' AS 'Record ID'
FROM
    [dbo].[2019-01]

---

我已经修改了我的查询，如下所示，它是有效的

select 
        [CompanyCode] as 'Company Code',
        [Sitecode] as 'Site Code',
        [Product] as 'Product Name',
        '' as 'Tank ID',
        CONVERT(date, [InvDay]) as  Date,

        SaleV=(CASE
                    WHEN [Sales] ='NULL' THEN 0
                     WHEN [Sales] = '' then 0
                    ELSE
                     CONVERT(decimal(10,4) ,[Sales] )
                     END)


    FROM [dbo].[2018-01]

---

您可以尝试此方法-修改您的查询。使用IsNull函数处理空值

select 
        [CompanyCode] as 'Company Code',
        [Sitecode] as 'Site Code',
        [Product] as 'Product Name',
        '' as 'Tank ID',
        CONVERT(date, [InvDay]) as  Date,
        CAST(ISNULL([Sales],0) as decimal(10,2)) as 'Sale Volume',
        '' as 'Record ID'
From [dbo].[2019-01]

注意：如果为空，上述查询将返回0.00，如果为字符串，则返回错误。要处理字符串值，请使用下面的查询，如果字符串为空，下面的查询将返回0.00，否则将转换为十进制

select 
        [CompanyCode] as 'Company Code',
        [Sitecode] as 'Site Code',
        [Product] as 'Product Name',
        '' as 'Tank ID',
        CONVERT(date, [InvDay]) as  Date,
        ISNULL(TRY_CAST([Sales] as decimal(10,2)), 0) as 'Sale Volume',
        '' as 'Record ID'
From [dbo].[2019-01]

---

您确定所有值都是十进制格式的吗？要克服此错误，请尝试使用try_cast并给出十进制精度，例如try_cast[Sales]为十进制10,5，以避免丢失任何十进制值，try_cast将通过将其转换为nulls@Avi谢谢，我提供了更新后的查询作为答案。try\u cast将在没有案例陈述的情况下执行相同/类似的操作