To DESC or @DESC...

There is one SQLPLUS command which seems to be out of my control as far as its displaying layout is concerned. As you already guess from the post title it's about the well known DESC command. Seems that it has a “self-tuning” layout which takes into consideration the current LINESIZE settings.

For example, using a high value for the LINESIZE setting we obtain:

scott@DDB> set linesize 300
scott@DDB> desc emp
 Name                                                                          
         Null?     Type
 ------------------------------------------------------------------------------
-------------------------------------------------------------------------------
---------------- -------- -----------------------------------------------------
---------------------------------------------------------------
 EMPNO                                                                         
         NOT NULL NUMBER(4)
 ENAME                                                                         
  VARCHAR2(10)
 JOB                                                                           
  VARCHAR2(9)
 MGR                                                                           
  NUMBER(4)
 HIREDATE                                                                      
  DATE
 SAL                                                                           
  NUMBER(7,2)
 COMM                                                                          
  NUMBER(7,2)
 DEPTNO                                                                        
  NUMBER(2)

But using a lower value for the LINESIZE setting the output looks fine:

scott@DDB> set linesize 80
scott@DDB> desc emp
 Name                                      Null?    Type
 ----------------------------------------- -------- ----------------------------
 EMPNO                                     NOT NULL NUMBER(4)
 ENAME                                              VARCHAR2(10)
 JOB                                                VARCHAR2(9)
 MGR                                                NUMBER(4)
 HIREDATE                                           DATE
 SAL                                                NUMBER(7,2)
 COMM                                               NUMBER(7,2)
 DEPTNO                                             NUMBER(2)

From my point of view this behavior is quite ugly especially when I am working within a console with horizontal scrolling capabilities. Using a high value for LINESIZE allows me to execute various 'SELECT * FROM' without worrying about output wrapping but when DESC command comes in place I will always end up scrolling to the right side till I reach the displaying of the columns type, which is really, really ugly! So, in the end I've decided to create a script which provides the expected nice output. The main idea is to decrease the LINESIZE setting, to execute DESC and then to restore the old LINESIZE setting. Not a big deal! Below is my script:

store set crr_settings.cfg replace
set linesize 80
desc &1
@crr_settings.cfg

Now, all I have to do is to take care to prefix with a @ the DESC command:

scott@DDB> set linesize 300
scott@DDB> @desc emp
Wrote file crr_settings.cfg
 Name                                      Null?    Type
 ----------------------------------------- -------- ----------------------------
 EMPNO                                     NOT NULL NUMBER(4)
 ENAME                                              VARCHAR2(10)
 JOB                                                VARCHAR2(9)
 MGR                                                NUMBER(4)
 HIREDATE                                           DATE
 SAL                                                NUMBER(7,2)
 COMM                                               NUMBER(7,2)
 DEPTNO                                             NUMBER(2)

Have fun! :)