问题：.net访问DB2提示“访问器验证被推迟。。。”

jasenkoo

在adapter.Fill(dt) 时报错：访问器验证被推迟，并在该方法返回数据时已执行。绑定对于此列或参数无效。
.net前台commandText为

SELECT 0 AS ROWNO,CODING AS ITEMCODE ,NAME AS ITEMNAME,PY_CODE, WB_CODE,'' AS D_CODE FROM BASE_DISEASE
或者
SELECT 0 AS ROWNO,CODING AS ITEMCODE ,NAME AS ITEMNAME,PY_CODE, WB_CODE,'' AS D_CODE FROM BASE_DISEASE
where SORT='B'
都没有问题

但是
SELECT 0 AS ROWNO,CODING AS ITEMCODE ,NAME AS ITEMNAME,PY_CODE, WB_CODE,'' AS D_CODE FROM BASE_DISEASE
where SORT='D'
有问题
.net取得DataTable方法：（部分代码）
public override DataTable GetDataTable(string  commandText)
{
OleDbCommand cmd=new OleDbCommand(commandText);
cmd.Connection=(OleDbConnection)this.connection;
if(isInTransaction) cmd.Transaction = (OleDbTransaction)transaction;

OleDbDataAdapter adapter = new OleDbDataAdapter((OleDbCommand)cmd);
try
{
  DataTable dt=new DataTable();
  adapter.Fill(dt);
  return dt;
}
catch(Exception err)
{
   throw new EntityException(err.Message);
}
finally
{
  cmd.Dispose();
  adapter.Dispose();
}
}