** When a public synonym has been created for an object, the synonym should be
   used instead of <schema>.<synonym>
   <schema>.<synonym> can be resolved in SQL*PLUS but not in PL/SQL.
   Since synonym is owned by 'PUBLIC', one can argue <schema>.<synonym> can not be
   resolved in PL/SQL. It is not clear how SQL*PLUS interprete <schema>.<synonym>.


SQL> conn jyang/jyang@athena
Connected.
SQL> grant select on test1 to scott;

Grant succeeded.

SQL> drop public synonym test1_syn;
drop public synonym test1_syn
                    *
ERROR at line 1:
ORA-01432: public synonym to be dropped does not exist 


SQL> create public synonym test1_syn for test1;

Synonym created.

SQL> 
SQL> conn scott/tiger@athena
Connected.
SQL> desc jyang.test1
 Name                                      Null?    Type
 ----------------------------------------- -------- ----------------------------
 C1                                                 VARCHAR2(2)
 C2                                                 NUMBER(1)
 SUMC2                                              NUMBER(5)

SQL> desc jyang.test1_syn
 Name                                      Null?    Type
 ----------------------------------------- -------- ----------------------------
 C1                                                 VARCHAR2(2)
 C2                                                 NUMBER(1)
 SUMC2                                              NUMBER(5)

SQL> desc test1_syn
 Name                                      Null?    Type
 ----------------------------------------- -------- ----------------------------
 C1                                                 VARCHAR2(2)
 C2                                                 NUMBER(1)
 SUMC2                                              NUMBER(5)

SQL> 
SQL> set serveroutput on
SQL> declare
  2  x number;
  3  begin
  4  select count(1) into x from jyang.test1;
  5  dbms_output.put_line('count jyang.test1= '||x);
  6  select count(1) into x from test1_syn;
  7  dbms_output.put_line('count test1_syn= '||x);
  8  end;
  9  /
count jyang.test1= 23                                                           
count test1_syn= 23                                                             

PL/SQL procedure successfully completed.

SQL> 
SQL> declare
  2  x number;
  3  begin
  4  select count(1) into x from jyang.test1_syn;
  5  dbms_output.put_line('count jyang.test1_syn= '||x);
  6  end;
  7  /
select count(1) into x from jyang.test1_syn;
                                  *
ERROR at line 4:
ORA-06550: line 4, column 35: 
PL/SQL: ORA-00942: table or view does not exist 
ORA-06550: line 4, column 1: 
PL/SQL: SQL Statement ignored 


SQL> 
SQL> conn jyang/jyang@athena
Connected.
SQL> drop public synonym test1_syn;

Synonym dropped.

SQL> create public synonym test1_syn for jyang.test1;

Synonym created.

SQL> 
SQL> conn scott/tiger@athena
Connected.
SQL> desc jyang.test1_syn
 Name                                      Null?    Type
 ----------------------------------------- -------- ----------------------------
 C1                                                 VARCHAR2(2)
 C2                                                 NUMBER(1)
 SUMC2                                              NUMBER(5)

SQL> desc test1_syn
 Name                                      Null?    Type
 ----------------------------------------- -------- ----------------------------
 C1                                                 VARCHAR2(2)
 C2                                                 NUMBER(1)
 SUMC2                                              NUMBER(5)

SQL> 
SQL> set serveroutput on
SQL> declare
  2  x number;
  3  begin
  4  select count(1) into x from test1_syn;
  5  dbms_output.put_line('count test1_syn= '||x);
  6  end;
  7  /
count test1_syn= 23                                                             

PL/SQL procedure successfully completed.

SQL> declare
  2  x number;
  3  begin
  4  select count(1) into x from jyang.test1_syn;
  5  dbms_output.put_line('count jyang.test1_syn= '||x);
  6  end;
  7  /
select count(1) into x from jyang.test1_syn;
                                  *
ERROR at line 4:
ORA-06550: line 4, column 35: 
PL/SQL: ORA-00942: table or view does not exist 
ORA-06550: line 4, column 1: 
PL/SQL: SQL Statement ignored 


SQL> 
SQL> conn jyang/jyang@athena
Connected.
SQL> drop public synonym test1_syn;

Synonym dropped.

SQL> 
SQL> spool off