关于image类型的动态sql请教大虾

create procedure P_UPLOADIMAGE
@InfoID as int,
@sTableName as varchar(50),
@sFieldName as varchar(50),
@UserImage as image
as
declare @sSql as varchar(500)
begin
--目的就是如下执行
update @sTableName
set @sFieldName = @UserImage
end

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create procedure P_UPLOADIMAGE
@InfoID as int,
@sTableName as varchar(50),
@sFieldName as varchar(50),
@UserImage as image
as
declare @sSql as Nvarchar(4000) --改变量定义
begin
set @sSql='update '+@sTableName+' set '+@sFieldName+' = @UserImage'
exec sp_executesql @sSql,N'@UserImage image',@UserImage
end
go

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--加上条件
create procedure P_UPLOADIMAGE
@InfoID as int,
@sTableName as varchar(50),
@sFieldName as varchar(50),
@UserImage as image
as
declare @sSql as Nvarchar(4000) --改变量定义
begin
set @sSql='update '+@sTableName+' set '+@sFieldName+' = @UserImage where id=@InfoID'
exec sp_executesql @sSql,N'@UserImage image,@InfoID int',@UserImage,@InfoID
end
go