The COUNT DB_DISCOVERY RULE syntax is used to query the number of database discovery rules for specified database.
CountDBDiscoveryRule::=
  'COUNT' 'DB_DISCOVERY' 'RULE' ('FROM' databaseName)?
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 | 
|---|---|
| rule_name | rule type | 
| database | the database to which the rule belongs | 
| count | the number of the rule | 
COUNT DB_DISCOVERY RULE FROM test1;
mysql> COUNT DB_DISCOVERY RULE FROM test1;
+--------------+----------+-------+
| rule_name    | database | count |
+--------------+----------+-------+
| db_discovery | test1    | 1     |
+--------------+----------+-------+
1 row in set (0.00 sec)
COUNT DB_DISCOVERY RULE;
mysql> COUNT DB_DISCOVERY RULE;
+--------------+----------+-------+
| rule_name    | database | count |
+--------------+----------+-------+
| db_discovery | test1    | 1     |
+--------------+----------+-------+
1 row in set (0.00 sec)
COUNT, DB_DISCOVERY, RULE, FROM
