The SHOW MASK RULES syntax is used to query mask rules for specified database.
ShowMaskRule::=
  'SHOW' 'MASK' ('RULES' | 'RULE' ruleName) ('FROM' databaseName)?
ruleName ::=
  identifier
databaseName ::=
  identifier
databaseName is not specified, the default is the currently used DATABASE. If DATABASE is not used, No database selected will be prompted.| Column | Description | 
|---|---|
| table | Table name | 
| column | Column name | 
| algorithm_type | Mask algorithm type | 
| algorithm_props | Mask algorithm properties | 
SHOW MASK RULES FROM mask_db;
mysql> SHOW MASK RULES FROM mask_db;
+---------+----------+------------------+--------------------------------+
| table   | column   | algorithm_type   | algorithm_props                |
+---------+----------+------------------+--------------------------------+
| t_mask  | phoneNum | MASK_FROM_X_TO_Y | to-y=2,replace-char=*,from-x=1 |
| t_mask  | address  | MD5              |                                |
| t_order | order_id | MD5              |                                |
| t_user  | user_id  | MASK_FROM_X_TO_Y | to-y=2,replace-char=*,from-x=1 |
+---------+----------+------------------+--------------------------------+
4 rows in set (0.01 sec)
SHOW MASK RULES;
mysql> SHOW MASK RULES;
+---------+----------+------------------+--------------------------------+
| table   | column   | algorithm_type   | algorithm_props                |
+---------+----------+------------------+--------------------------------+
| t_mask  | phoneNum | MASK_FROM_X_TO_Y | to-y=2,replace-char=*,from-x=1 |
| t_mask  | address  | MD5              |                                |
| t_order | order_id | MD5              |                                |
| t_user  | user_id  | MASK_FROM_X_TO_Y | to-y=2,replace-char=*,from-x=1 |
+---------+----------+------------------+--------------------------------+
4 rows in set (0.01 sec)
SHOW MASK RULE t_mask FROM mask_db;
mysql> SHOW MASK RULE t_mask FROM mask_db;
+--------+--------------+------------------+--------------------------------+
| table  | logic_column | mask_algorithm   | props                          |
+--------+--------------+------------------+--------------------------------+
| t_mask | phoneNum     | MASK_FROM_X_TO_Y | to-y=2,replace-char=*,from-x=1 |
| t_mask | address      | MD5              |                                |
+--------+--------------+------------------+--------------------------------+
2 rows in set (0.00 sec)
SHOW MASK RULE t_mask;
mysql> SHOW MASK RULE t_mask;
+--------+--------------+------------------+--------------------------------+
| table  | logic_column | mask_algorithm   | props                          |
+--------+--------------+------------------+--------------------------------+
| t_mask | phoneNum     | MASK_FROM_X_TO_Y | to-y=2,replace-char=*,from-x=1 |
| t_mask | address      | MD5              |                                |
+--------+--------------+------------------+--------------------------------+
2 rows in set (0.00 sec)
SHOW, MASK, RULE, RULES, FROM
