The REGISTER STORAGE UNIT syntax is used to register storage unit for the currently selected logical database.
RegisterStorageUnit ::=
  'REGISTER' 'STORAGE' 'UNIT' ifNotExists? storageUnitDefinition (',' storageUnitDefinition)*
storageUnitDefinition ::=
  storageUnitName '(' ('HOST' '=' hostName ',' 'PORT' '=' port ',' 'DB' '=' dbName | 'URL' '=' url) ',' 'USER' '=' user (',' 'PASSWORD' '=' password)? (',' propertiesDefinition)?')'
ifNotExists ::=
  'IF' 'NOT' 'EXISTS'
storageUnitName ::=
  identifier
hostname ::=
  string
    
port ::=
  int
dbName ::=
  string
url ::=
  string
user ::=
  string
password ::=
  string
propertiesDefinition ::=
  'PROPERTIES' '(' key '=' value (',' key '=' value)* ')'
key ::=
  string
value ::=
  literal
use command to
successfully select a database;storageUnitName is case-sensitive;storageUnitName needs to be unique within the current database;storageUnitName name only allows letters, numbers and _, and must start with a letter;poolProperty is used to customize connection pool parameters, key must be the same as the connection pool
parameter name;ifNotExists clause is used for avoid Duplicate storage unit error.REGISTER STORAGE UNIT ds_0 (
    HOST="127.0.0.1",
    PORT=3306,
    DB="db_1",
    USER="root",
    PASSWORD="root"
);
REGISTER STORAGE UNIT ds_0 (
    HOST="127.0.0.1",
    PORT=3306,
    DB="db_1",
    USER="root",
    PASSWORD="root",
    PROPERTIES("maximumPoolSize"=10)
);
REGISTER STORAGE UNIT ds_0 (
    URL="jdbc:mysql://127.0.0.1:3306/db_2?serverTimezone=UTC&useSSL=false",
    USER="root",
    PASSWORD="root",
    PROPERTIES("maximumPoolSize"=10,"idleTimeout"="30000")
);
ifNotExists clauseREGISTER STORAGE UNIT IF NOT EXISTS ds_0 (
    HOST="127.0.0.1",
    PORT=3306,
    DB="db_0",
    USER="root",
    PASSWORD="root"
);
REGISTER, STORAGE, UNIT, HOST, PORT, DB, USER, PASSWORD, PROPERTIES, URL
