The DROP SHARDING TABLE REFERENCE RULE syntax is used to drop specified sharding table reference rule.
DropShardingTableReferenceRule ::=
  'DROP' 'SHARDING' 'TABLE' 'REFERENCE' 'RULE'  ruleName (',' ruleName)*
ruleName ::=
  identifier
DROP SHARDING TABLE REFERENCE RULE ref_0;
DROP SHARDING TABLE REFERENCE RULE ref_0, ref_1;
DROP, SHARDING, TABLE, REFERENCE, RULE
