Oracle SQL: Why are column headers missing?

Question

I want to understand why my columns are missing their headers.

Consider this table:

SQL> DESC customer;
Name Null? Type 
------------ -------- ------------ 
CUST_ID NOT NULL NUMBER(5) 
CUST_NAME VARCHAR2(15) 
ACCOUNT_ID VARCHAR2(10) 
ACCOUNT_TYPE VARCHAR2(2) 
STATE VARCHAR2(2) 

When I select * from the table, the result is missing the column headers.

SQL> SELECT * FROM customer;
 90001 B and B A-11101 PR AK
 90002 XYZ A-11102 CM NJ
 90003 JJ Sons A-11103 CM NJ
 90004 Exxon A-11104 PR NY
 90005 ABC A-11105 CM NY
 90006 Smith Co. A-11106 CM MD
 90007 Brown Co. A-11107 CM MD
 90008 Cooper Inc. A-11108 PR MD
8 rows selected. 

Why?

My goal is to display the tables with the headers. If there are other details I need to add, let me know.

Answer 1

Heading may be disabled in your environment. Enable it (it is enabled by default).

SQL> select banner from v$version;
Oracle Database 12c Enterprise Edition Release 12.1.0.2.0 - 64bit Production
PL/SQL Release 12.1.0.2.0 - Production
CORE 12.1.0.2.0 Production
TNS for Linux: Version 12.1.0.2.0 - Production
NLSRTL Version 12.1.0.2.0 - Production
SQL> show heading
heading OFF
SQL> set heading on
SQL> select banner from v$version;
BANNER
--------------------------------------------------------------------------------
Oracle Database 12c Enterprise Edition Release 12.1.0.2.0 - 64bit Production
PL/SQL Release 12.1.0.2.0 - Production
CORE 12.1.0.2.0 Production
TNS for Linux: Version 12.1.0.2.0 - Production
NLSRTL Version 12.1.0.2.0 - Production

Or pagesize is set 0:

SQL> show heading pagesize
heading ON
pagesize 14
SQL> set pagesize 0
SQL> select banner from v$version;
Oracle Database 12c Enterprise Edition Release 12.1.0.2.0 - 64bit Production
PL/SQL Release 12.1.0.2.0 - Production
CORE 12.1.0.2.0 Production
TNS for Linux: Version 12.1.0.2.0 - Production
NLSRTL Version 12.1.0.2.0 - Production
SQL> set pagesize 14
SQL> select banner from v$version;
BANNER
--------------------------------------------------------------------------------
Oracle Database 12c Enterprise Edition Release 12.1.0.2.0 - 64bit Production
PL/SQL Release 12.1.0.2.0 - Production
CORE 12.1.0.2.0 Production
TNS for Linux: Version 12.1.0.2.0 - Production
NLSRTL Version 12.1.0.2.0 - Production

• NonCreature0714: I just used show heading and it reports that heading ON
• Balazs Papp: @NonCreature0714 Try pagesize next.
• NonCreature0714: That was it, my pagesize was set to 0