You need to set property "FirstNormalForm=false" in U2ConnectionStringBuilder Class. For example:
U2ConnectionStringBuilder conn_str = new U2ConnectionStringBuilder();
conn_str.UserID = "user";
conn_str.Password = "pass";
conn_str.Server = "localhost";
conn_str.Database = "XDEMO";
conn_str.ServerType = "UNIVERSE";
conn_str.FirstNormalForm = false;
U2Connection con = new U2Connection();
con.ConnectionString = conn_str.ToString();
con.Open();
.......
For UniVerse Database:
SQL Statement : SELECT FNAME,PRICE,BUY_DATE FROM UNNEST CUSTOMER ON ORDERS
(PRICE and BUY_DATE are multi-valued attributes)
For UniData Database:
SQL Statement : SELECT * FROM STUDENT UNNEST NL_ALL CGA
(FNAME,...,SEMESTER are multi-valued attributes)