对字符型，用axx格式，对数字型，用9999 格式(999表示占用3列)
SQL> col 'ts#' format 999
SQL> col 'file#' format 999
SQL> col 'name' format a50
SQL> select ts#,file#,name from v$datafile;
TS# FILE# NAME
---- ----- --------------------------------------------------
0 1 /u01/app/oracle/oradata/orcl/system01.dbf
1 2 /u01/app/oracle/oradata/orcl/sysaux01.dbf
2 3 /u01/app/oracle/oradata/orcl/undotbs01.dbf
4 4 /u01/app/oracle/oradata/orcl/users01.dbf
6 5 /u01/app/oracle/oradata/orcl/example01.dbf
SQL>