Storing values of one numeric data type in columns of another numeric data type

An attempt to put a floating-point type of a larger storage size into a location of a smaller size fails only if the value cannot be stored in the smaller-size location. For example:

create table mytable (r REAL, d DOUBLE PRECISION);
0 rows inserted/updated/deleted
INSERT INTO mytable (r, d) values (3.4028236E38, 3.4028235E38);
ERROR X0X41: The number '3.4028236E38' is outside the range for
the data type REAL.

You can store a floating point type in an INTEGER column; the fractional part of the number is truncated. For example:

INSERT INTO mytable(integer_column) values (1.09e0);
1 row inserted/updated/deleted
SELECT integer_column
FROM mytable;
I
---------------
1

Integers can be stored in decimals if the DECIMAL precision is large enough for the value. For example:

ij> insert into mytable (decimal_column)
VALUES (55555555556666666666);
ERROR X0Y21: The number '55555555556666666666' is outside the
range of the target DECIMAL/NUMERIC(5,2) datatype.

An attempt to put an integer value of a larger storage size into a location of a smaller size fails if the value cannot be stored in the smaller-size location. For example:

INSERT INTO mytable (int_column) values 2147483648;
ERROR 22003: The resulting value is outside the range for the 
data type INTEGER.