9.3.10 DOUBLE

The JDBC type DOUBLE represents a "double precision" floating point number that supports 15 digits of mantissa.
The corresponding SQL type is DOUBLE PRECISION, which is defined in SQL-92 and is widely supported by the major databases. The SQL-92 standard leaves the precision of DOUBLE PRECISION up to the implementation, but in practice all the major databases supporting DOUBLE PRECISION support a mantissa precision of at least 15 digits.
The recommended Java mapping for the DOUBLE type is as a Java double.