the column names removed after insert select

[patcharee]

Hi

I inserted a table from select (insert into table newtable select date, 
hh, x, y from oldtable). After the insert the column names of the table 
have been removed, see the output below when I use hive --orcfiledump

- Type: struct<_col0:int,_col1:int,_col2:int,_col3:int>

while it is supposed to be

- Type: struct<date:int,hh:int,x:int,y:int>

Any ideas how this happened and how I can fix it. Please suggest me.

BR,
Patcharee