将参数值从字符串转换为Byte[]失败

Question

net代码，当我试图插入二进制格式的字符串时，我就会遇到这个问题。

我有二进制格式的图像在decal.DecalLogoFileName和decal.DecalLogoFileName是定义一个字符串，所以当我尝试作为

cmd.Parameters.Add(new SqlParameter("@DecalLogoFileName", SqlDbType.Binary)).Value=decal.DecalLogoFileName;

decal.DecalLogoFileName="data:image/jpeg;base64,/9j/4AAQSkZJRgABAQAAAQABAAD/2wCEAAkGBxITEhUTExIWFhUXGB8aGBcYGR0ZHxobGhoXHRcYGBkaHyghHRolHRcXIjEhJSkrLi4uGB8zODMtNygtLisBCgoKDg0OGhAQGy0lHyUtLS0tLS0tLS0tLS0tLy0tLS0tLS0tLS0tLS0tLS0tLS0tLS0tLSstLS0tLS0tLS0tLf/AABEIALcBEwMBIgACEQEDEQH/xAAbAAACAwEBAQAAAAAAAAAAAAAEBQIDBgABB//EAEgQAAIBAgQDBQQHBQYDCAMAAAECEQADBBIhMQVBUQYTImFxMoGRoSNCUrHB0fAUcpLS4QczU2KCshVUc0Njg5OiwuLxFiRk/8QAGQEAAwEBAQAAAAAAAAAAAAAAAQIDAAQF/8QALBEAAgICAgECBQQCAwAAAAAAAAECERIhAzFBE2EiMlFxgUKhsdEEkSMzUv/aAAwDAQACEQMRAD8A"

我是贴花中的字符串值为

function readURL(input) {
if (input.files && input.files[0]) {
        var reader = new FileReader();
        reader.onload = function (e) {
            $('#DecalLogo').attr('src', e.target.result);
            $('#hdImageName').val(e.target.result);
        }
        reader.readAsDataURL(input.files[0]);
    }
}

这里，hdImageName值存储在decal.DecalLogoFileName中

我也试过

cmd.Parameters.Add(new SqlParameter("@DecalLogoFileName", SqlDbType.Binary)).Value=Convert.toByte(decal.DecalLogoFileName);

但转换问题即将到来。

DecalLogoFileName的列数据类型设置为varbinary(MAX)