GROUP BY empty grouping set

SELECT COUNT(*)
FROM BOOK
GROUP BY ()
 

create.selectCount()
      .from(BOOK)
      .groupBy()
      .fetch();

selectCount().from(BOOK).groupBy()

-- ACCESS
SELECT count(*)
FROM BOOK, (select count(*) dual from MSysResources) as empty_grouping_dummy_table
GROUP BY empty_grouping_dummy_table.dual

-- ASE, BIGQUERY, SQLDATAWAREHOUSE
SELECT count(*)
FROM BOOK, (select 1 as dual) as empty_grouping_dummy_table
GROUP BY empty_grouping_dummy_table.dual

-- AURORA_MYSQL, MEMSQL
SELECT count(*)
FROM BOOK
GROUP BY (SELECT 1
FROM DUAL)

-- AURORA_POSTGRES, DB2, DUCKDB, EXASOL, H2, ORACLE, POSTGRES, SQLSERVER, SYBASE, TERADATA, TRINO
SELECT count(*)
FROM BOOK
GROUP BY ()

-- COCKROACHDB, MARIADB, MYSQL, REDSHIFT, SQLITE, VERTICA, YUGABYTEDB
SELECT count(*)
FROM BOOK
GROUP BY (SELECT 1)

-- DERBY, HSQLDB
SELECT count(*)
FROM BOOK
GROUP BY 0

-- FIREBIRD
SELECT count(*)
FROM BOOK
GROUP BY (SELECT 1
FROM RDB$DATABASE)

-- HANA, SNOWFLAKE
SELECT count(*)
FROM BOOK
GROUP BY GROUPING SETS (())

-- INFORMIX
SELECT count(*)
FROM BOOK, (select 1 as dual from systables where tabid = 1) as empty_grouping_dummy_table
GROUP BY empty_grouping_dummy_table.dual