无法将数据类型 nvarchar 转换为数字

我使用以下查询将数据从Excel文件导入SQL Server数据库。Excel 文件将所有值作为字符串类型（'在每个单元格之前

）。

导入时出现此错误。无法将数据类型 nvarchar 转换为数字"

如果我从导入中删除销售价格和价格 2 两列，则导入成功。

我的表的数据类型是

CREATE TYPE [dbo].[InventoryType] AS TABLE
(
   [LocalSKU] [varchar](200) NOT NULL,
   [ItemName] [varchar](200) NULL,
   [QOH] [int] NULL,
   [Price] [decimal](19, 4) NULL,
   [Discontinued] [bit] NULL,
   [Barcode] [varchar](25) NULL,
   [Integer2] [int] NULL,
   [Integer3] [int] NULL,
   [SalePrice] [decimal](19, 4) NULL,
   [SaleOn] [bit] NULL,
   [Price2] [decimal](19, 4) NULL
)
GO

我使用的查询是：

SqlCommand sqlcmd = new SqlCommand
   (@"MERGE Inventory AS target
      USING (SELECT
                LocalSKU, ItemName, QOH, Price, Discontinued, 
                Barcode, Integer2, Integer3, SalePrice, SaleOn, Price2 
             FROM @source) AS Source ON (Source.LocalSKU = target.LocalSKU)
      WHEN MATCHED THEN
         UPDATE 
           SET ItemName = source.ItemName,
               Price = source.Price,
               Discontinued = source.Discontinued,
               Barcode = source.Barcode,
               Integer2 = source.Integer2,
               Integer3 = source.QOH,
               SalePrice = source.SalePrice,
               SaleOn = source.SaleOn,
               Price2 = source.Price2;", sqlconn);
SqlParameter param;
param = sqlcmd.Parameters.AddWithValue("@source", dr);
param.SqlDbType = SqlDbType.Structured;
param.TypeName = "dbo.InventoryType";
sqlconn.Open();
sqlcmd.ExecuteNonQuery();
sqlconn.Close();