COUNT DB_DISCOVERY RULE 语法用于查询指定逻辑库中的数据库发现规则数量。
CountDBDiscoveryRule::=
'COUNT' 'DB_DISCOVERY' 'RULE' ('FROM' databaseName)?
databaseName ::=
identifier
databaseName 时，默认是当前使用的 DATABASE。 如果也未使用 DATABASE 则会提示 No database selected。| 列 | 说明 |
|---|---|
| rule_name | 规则类型 |
| database | 规则所属逻辑库 |
| count | 规则数量 |
COUNT DB_DISCOVERY RULE FROM discovery_db;
mysql> COUNT DB_DISCOVERY RULE FROM discovery_db;
+--------------+-----------------+-------+
| rule_name | database | count |
+--------------+-----------------+-------+
| db_discovery | discovery_db | 1 |
+--------------+-----------------+-------+
1 row in set (0.00 sec)
COUNT DB_DISCOVERY RULE;
mysql> COUNT DB_DISCOVERY RULE;
+--------------+-----------------+-------+
| rule_name | database | count |
+--------------+-----------------+-------+
| db_discovery | discovery_db | 1 |
+--------------+-----------------+-------+
1 row in set (0.00 sec)
COUNT、DB_DISCOVERY、RULE、FROM