ORACLE insert into 報錯 invalid identifier

insert into "xxxx"."xxxx"(f_Stat_Date, f_File_Type, f_Time, f_Total_Size) values( to_date('2008-01-25 12:39:49','YYYY-MM-DD HH24:MI:SS'),1,to_date('2008-01-25 12:39:49','YYYY-MM-DD HH24:MI:SS'),100) 
命令出錯, 行: 2 列: 77
錯誤報表:
SQL 錯誤: ORA-00904: "F_TOTAL_SIZE": invalid identifier
00904. 00000 -  "%s: invalid identifier"
*Cause:    

*Action:

更改為 

insert into "xxxx"."xxxx"("f_Stat_Date", "f_File_Type","f_Time","f_Total_Size") values( to_date('2008-01-25 12:39:49','YYYY-MM-DD HH24:MI:SS'),1,to_date('2008-01-25 12:39:49','YYYY-MM-DD HH24:MI:SS'),100);

成功。。。。  看來還是要加""啊