Column Name beginning with a number?

Question

I have a column name in one of my tables called: 3RD_DIAG_CODE - VARCHAR2 (10 Byte)

When I try to run a query, it gives me the following error highlight

Answer 1

You probably have two columns listed without a comma between them.

create table t (id number primary key, 3d varchar2(30))
Error at Command Line:1 Column:39
Error report:
SQL Error: ORA-00904: : invalid identifier
00904. 00000 -  "%s: invalid identifier"


create table t (id number primary key, "3d" varchar2(30));
table T created.
desc t
Name Null     Type         
---- -------- ------------ 
ID   NOT NULL NUMBER       
3d            VARCHAR2(30) 


> select id, 3d from t --[as @gsiem mentions: THIS IS BAD]
ID                     3D       
---------------------- -------- 

> select id, "3d" from t
ID                     3d                             
---------------------- ------------------------------ 

> select id, [3d] from t

Error starting at line 7 in command:
select id, [3d] from t
Error at Command Line:7 Column:11
Error report:
SQL Error: ORA-00936: missing expression
00936. 00000 -  "missing expression"
*Cause:    
*Action:
> select id 3d from t

Error starting at line 8 in command:
select id 3d from t
Error at Command Line:8 Column:10
Error report:
SQL Error: ORA-00923: FROM keyword not found where expected
00923. 00000 -  "FROM keyword not found where expected"
*Cause:    
*Action: