Get Byte[] from Db2 without Encoding

问题

In GetEmpIDInBytes_INDIRECT method listed below, I get the following exception:

Unable to cast object of type 'System.String' to type 'System.Byte[]'.

I know that this error can be avoided if I use the following line (i.e. encoding instead of byte[] casting)

result = Encoding.ASCII.GetBytes(odbcCommand.ExecuteScalar().ToString());

But I cannot use the encoding since I don’t know what was the encoding used in the DB2 function. I need to get it back from DB2 as byte[]. How can we get it?

CODE

string sqlGetEncryptedEmpID_INDIRECT = String.Format(SQLGetEncryptedID_INDIRECT, empIDClearText);
byte[] empIDData_INDIRECT = (byte[])GetEmpIDInBytes_INDIRECT(sqlGetEncryptedEmpID_INDIRECT);



public const string SQLGetEncryptedID_INDIRECT = @"SELECT  SSS.id_encrypt ('E','0000000{0}') 
                                                AS ENCRYPT_ID FROM FFGLOBAL.ONE_ROW FETCH FIRST 1 ROW ONLY WITH UR;";



private byte[] GetEmpIDInBytes_INDIRECT(string sqlQuery)
    {
        byte[] result = null;
        string db2connectionString = ConfigurationManager.ConnectionStrings[UIConstants.DB2ConnectionString].ConnectionString;
        using (OdbcConnection odbcConnection = new OdbcConnection(db2connectionString))
        {
            using (OdbcCommand odbcCommand = new OdbcCommand(sqlQuery, odbcConnection))
            {
                odbcCommand.CommandType = System.Data.CommandType.Text;
                odbcConnection.Open();
                result = (byte[])odbcCommand.ExecuteScalar();
                //result = Encoding.ASCII.GetBytes(odbcCommand.ExecuteScalar().ToString());
            }
        }
        return result;
}

DB2 Connection String

<add name="DB2ConnectionString_XA"
connectionString="Driver={IBM DB2 ODBC DRIVER};Database=MyDB;Hostname=DB2GWTST;
Protocol=TCPIP;Port=3700;Uid=remotxa;Pwd=xxxx;"/>

回答1:

Consider the following method (use this answer as a reference):

static byte[] GetBytes(string str)
{
    byte[] bytes = new byte[str.Length * sizeof(char)];
    System.Buffer.BlockCopy(str.ToCharArray(), 0, bytes, 0, bytes.Length);
    return bytes;
}

Use it like this:

result = GetBytes(odbcCommand.ExecuteScalar().ToString());

回答2:

At the end, I used CAST AS CHAR(100) FOR BIT DATA in the Db2 query itself. That worked.

public const string SQLGetEncryptedIDDirect =
@"SELECT  CAST ( SSS.id_encrypt ('E','0000000{0}') AS CHAR(100) FOR BIT DATA)  
AS ENCRYPT_ID FROM FFGLOBAL.ONE_ROW FETCH     FIRST 1 ROW ONLY WITH UR;";

来源：https://stackoverflow.com/questions/15153100/get-byte-from-db2-without-encoding

标签

db2