COUNT SHARDING RULE
Description
The COUNT SHARDING RULE
syntax is used to query the number of sharding rules for specified database.
Syntax
Grammar Railroad diagram
CountShardingRule::=
'COUNT' 'SHARDING' 'RULE' ('FROM' databaseName)?
databaseName ::=
identifier
Supplement
- When
databaseName
is not specified, the default is the currently usedDATABASE
. IfDATABASE
is not used,No database selected
will be prompted.
Return value description
Column | Description |
---|---|
rule_name | rule type |
database | the database to which the rule belongs |
count | the number of the rule |
Example
- Query the number of sharding rules for specified database.
COUNT SHARDING RULE FROM sharding_db;
mysql> COUNT SHARDING RULE FROM sharding_db;
+--------------------------+----------------+-------+
| rule_name | database | count |
+--------------------------+----------------+-------+
| sharding_table | sharding_db | 2 |
| sharding_table_reference | sharding_db | 2 |
+--------------------------+----------------+-------+
2 rows in set (0.00 sec)
- Query the number of sharding rules for current database.
COUNT SHARDING RULE;
mysql> COUNT SHARDING RULE;
+--------------------------+----------------+-------+
| rule_name | database | count |
+--------------------------+----------------+-------+
| sharding_table | sharding_db | 2 |
| sharding_table_reference | sharding_db | 2 |
+--------------------------+----------------+-------+
2 rows in set (0.00 sec)
Reserved word
COUNT
, SHARDING
, RULE
, FROM
Related links
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