The DROP DEFAULT SHARDING STRATEGY syntax is used to drop default sharding strategy for specified database.
DropDefaultShardingStrategy ::=
  'DROP' 'DEFAULT' 'SHARDING' ('TABLE' | 'DATABASE') 'STRATEGY' ifExists? ('FROM' databaseName)?
ifExists ::=
  'IF' 'EXISTS'
databaseName ::=
  identifier
databaseName is not specified, the default is the currently used DATABASE. If DATABASE is not used, No database selected will be prompted;ifExists clause is used for avoid Default sharding strategy not exists error.DROP DEFAULT SHARDING TABLE STRATEGY FROM sharding_db;
DROP DEFAULT SHARDING DATABASE STRATEGY;
ifExists clauseDROP DEFAULT SHARDING TABLE STRATEGY IF EXISTS;
ifExists clauseDROP DEFAULT SHARDING DATABASE STRATEGY IF EXISTS;
DROP, DEFAULT , SHARDING, TABLE, DATABASE ,STRATEGY, FROM
