I have to find the primary key of a table in oracle and I am typing this command SELECT * FROM ALL_CONS_COLUMN S A JOIN ALL_CONSTRAINTS C ON A.CONSTRAINT_NA ME = C.CONSTRAINT_NA ME WHERE C.TABLE_NAME = ACTIVE_MAINTENA NCE_REQUEST AND C.CONSTRAINT_TY PE = 'P';

but it is giving the error
ERROR at line 1:
ORA-00904: "ACTIVE_MAINTEN ANCE_REQUEST": invalid identifier