MySQL 8.3 Release Notes
给定一个模式名，该过程将创建一个包含所有原始模式表和视图的同义词模式视图。这可以用于例如，创建一个较短的名称，以便引用一个长名称的模式（例如，info 而不是 INFORMATION_SCHEMA）。
mysql> SHOW DATABASES;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| sys |
| world |
+--------------------+
mysql> CALL sys.create_synonym_db('INFORMATION_SCHEMA', 'info');
+---------------------------------------+
| summary |
+---------------------------------------+
| Created 63 views in the info database |
+---------------------------------------+
mysql> SHOW DATABASES;
+--------------------+
| Database |
+--------------------+
| information_schema |
| info |
| mysql |
| performance_schema |
| sys |
| world |
+--------------------+
mysql> SHOW FULL TABLES FROM info;
+---------------------------------------+------------+
| Tables_in_info | Table_type |
+---------------------------------------+------------+
| character_sets | VIEW |
| collation_character_set_applicability | VIEW |
| collations | VIEW |
| column_privileges | VIEW |
| columns | VIEW |
...