SQL in Oracle: Decode function not working in this scenario

Question

This is my table productinfo. When using decode function to change the type column,the following error occurs.

MAKER      MODEL      TYPE
---------- ---------- -----
ibm        pc112      pc
ibm        lp113      pc
zenith     pr114      pr
wipro      pc122      pc
wipro      lp123      lp
wipro      pr124      pr
ibm        pc134      pc
ibm        lp114      lp
ibm        pc132      pc
ibm        lp133      lp
ibm        pr134      pr

11 rows selected.

SQL> savepoint prodinfopre;

Savepoint created.

SQL> select maker,model,decode(type,'lp','laptop','pr','printer', 'pc','personal
 computer') as "TYPE"  from productinfo;

MAKER      MODEL      TYPE
---------- ---------- -----------------
ibm        pc112
ibm        lp113
zenith     pr114
wipro      pc122
wipro      lp123
wipro      pr124
ibm        pc134
ibm        lp114
ibm        pc132
ibm        lp133
ibm        pr134

11 rows selected.

Answer 1

Try using trim for remove space

select maker,model
 ,decode(trim(type),'lp','laptop','pr','printer', 'pc','personal computer') as "TYPE"  

from productinfo;