判段某一列值是否为空时出现错误
判段某一列值是否为空时出现异常。程序 if (sread[head_picture]System.DBNull.Value)出现异常Invalid
判段某一列值是否为空时出现异常。
程序
if (sread["head_picture"]==System.DBNull.Value)
出现异常Invalid attempt to read when no data is present.
还有一个问题。
string sql1 = "insert into users (username,passward,permission,head_picture,mypaper) values ('" + name + "','" + passward + "',0,'@images','" + mypaper + "')";
FileStream fs = File.OpenRead(../../image/1.jpg);
byte[] imageb = new byte[fs.Length];
fs.Read(imageb, 0, imageb.Length);
fs.Close();
SqlCommand com3 = new SqlCommand(sql1, conn);
com3.Parameters.Add("@images", SqlDbType.Image).Value = imageb;
if (com3.Connection.State == ConnectionState.Closed)
com3.Connection.Open();
try
{
com3.ExecuteNonQuery();
}
为什么把图片存到数据库里数据不对 sql
[解决办法]if (string.IsEmptyOrWhiteSpace(sread["head_picture"]))
{
}
[解决办法]sread是否是DataRow对象? 确认其是否有数据来源.
用法举例
foreach (DataRow sread in [DataSet对象].Tables[0].Rows)
{
if (sread["head_picture"]== System.DBNull.Value)
{
...
}
}
[解决办法]参考 http://hi.baidu.com/keepzeal/item/3faa65106665cd5c2b3e2270