Oracle sets the display width of the query field

 normal query

SQL> select *  from scan_users;

USERID               USERNAME             USERPWD
-------------------- -------------------- --------------------
SUPER                超级管理员           SUPER

Display the userid column 3 widths. 

SQL> col userid for a3
SQL> run
  1* select *  from scan_users

USE USERNAME             USERPWD
--- -------------------- --------------------
SUP 超级管理员           SUPER
ER