[CBRD-24371] In alter synonym, comments can be changed without a for clause, and empty string comments become NULL.

[youngjinj]

http://jira.cubrid.org/browse/CBRD-24371

In alter synonym, comments can be changed without a for clause, and empty string comments become NULL.

1. In AS-IS, only the comment could not be changed when the ALTER SYNONYM statement was executed.

csql> create synonym s1 for t1;
csql> alter synonym s1 comment 'Change comment without for clause.';

ERROR: Invalid alter synonym.
  ALTER [PRIVATE] SYNONYM [<user_name>.]<synonym_name> FOR [<user_name>.]<target_name> [COMMENT 'comment_string']

In To-BE

1. When executing the ALTER SYNONYM statement, only the comment can be changed without using the for clause.

/* AS-IS */
ALTER [PRIVATE] SYNONYM [<user_name>.]<synonym_name> FOR [<user_name>.]<target_name> [COMMENT 'comment_string']

/* TO-BE */
ALTER [PRIVATE] SYNONYM [<schema_name>.]<synonym_name> {FOR [<schema_name>.]<target_name> [COMMENT 'comment_string'] | COMMENT 'comment_string'}

2. In the ALTER SYNONYM statement, if there is no for clause and no comments are changed, an error should occur.
   • MSGCAT_SYNTAX_SYNONYM_ALTER_NO_OPTION

csql> create synonym s2 for t2;
csql> alter synonym s2;
    
ERROR: No options specified for ALTER SYNONYM.

3. If the comment of synonym is changed to an empty string, it becomes NULL.

   3.1. CREATE SYNONYM with empty string as comment.

   csql> create synonym s3 for t3 comment '';
   csql> select * from db_synonym where synonym_name = 's3';
   
   /* AS-IS */
     synonym_name  synonym_owner_name  is_public_synonym  target_name  target_owner_name  comment
   ================================================================================================
     's3'          'PUBLIC'            'NO'               't3'         'PUBLIC'           ''
   
   /* TO-BE */
     synonym_name  synonym_owner_name  is_public_synonym  target_name  target_owner_name  comment
   ================================================================================================
     's3'          'PUBLIC'            'NO'               't3'         'PUBLIC'           NULL
   

   3.2. ALTER SYNONYM with empty string as comment.

   csql> create synonym s4 for t4 comment 'dummy comment.';
   csql> select * from db_synonym where synonym_name = 's4';
   
     synonym_name  synonym_owner_name  is_public_synonym  target_name  target_owner_name  comment
   =========================================================================================================
     's4'          'PUBLIC'            'NO'               't4'         'PUBLIC'           'Dummy comment.'
   
   csql> alter synonym s4 for t4 comment '';
   csql> select * from db_synonym where synonym_name = 's4';
   
   /* AS-IS */
     synonym_name  synonym_owner_name  is_public_synonym  target_name  target_owner_name  comment
   =========================================================================================================
     's4'          'PUBLIC'            'NO'               't4'         'PUBLIC'           ''
   
   /* TO-BE */
     synonym_name  synonym_owner_name  is_public_synonym  target_name  target_owner_name  comment
   =========================================================================================================
     's4'          'PUBLIC'            'NO'               't4'         'PUBLIC'           NULL
   

[codecov-commenter]

Codecov Report

Merging #3694 (20f105a) into develop (aa38779) will decrease coverage by 1.88%.
The diff coverage is 0.88%.

@@             Coverage Diff             @@
##           develop    #3694      +/-   ##
===========================================
- Coverage    50.91%   49.02%   -1.89%     
===========================================
  Files          515      515              
  Lines       398190   398213      +23     
===========================================
- Hits        202726   195232    -7494     
- Misses      195464   202981    +7517     

Impacted Files	Coverage Δ
src/parser/parse_tree_cl.c	66.41% <0.00%> (-3.04%)	⬇️
src/parser/semantic_check.c	63.52% <0.00%> (-4.66%)	⬇️
src/query/execute_statement.c	52.56% <0.00%> (-3.90%)	⬇️
src/parser/parser_support.c	60.51% <2.32%> (-3.32%)	⬇️
src/method/method_def.hpp	0.00% <0.00%> (-100.00%)	⬇️
src/method/method_def.cpp	18.18% <0.00%> (-68.69%)	⬇️
src/method/method_connection_pool.cpp	6.12% <0.00%> (-59.19%)	⬇️
src/query/query_hash_scan.c	7.43% <0.00%> (-51.60%)	⬇️
src/method/method_struct_invoke.cpp	34.44% <0.00%> (-33.34%)	⬇️
src/object/object_printer.cpp	48.58% <0.00%> (-25.06%)	⬇️
... and 126 more

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