How to get primary key column in Oracle?

Same as the answer from 'Richie' but a bit more concise.

1. Query for user constraints only

   SELECT column_name FROM all_cons_columns WHERE constraint_name = (
     SELECT constraint_name FROM user_constraints 
     WHERE UPPER(table_name) = UPPER('tableName') AND CONSTRAINT_TYPE = 'P'
   );
   

2. Query for all constraints

   SELECT column_name FROM all_cons_columns WHERE constraint_name = (
     SELECT constraint_name FROM all_constraints 
     WHERE UPPER(table_name) = UPPER('tableName') AND CONSTRAINT_TYPE = 'P'
   );
   

Select constraint_name,constraint_type from user_constraints where table_name** **= ‘TABLE_NAME’ ;

(This will list the primary key and then)

Select column_name,position from user_cons_columns where constraint_name=’PK_XYZ’; 

(This will give you the column, here PK_XYZ is the primay key name)

SELECT cols.table_name, cols.column_name, cols.position, cons.status, cons.owner
FROM all_constraints cons, all_cons_columns cols
WHERE cols.table_name = 'TABLE_NAME'
AND cons.constraint_type = 'P'
AND cons.constraint_name = cols.constraint_name
AND cons.owner = cols.owner
ORDER BY cols.table_name, cols.position;

Make sure that 'TABLE_NAME' is in upper case since Oracle stores table names in upper case.