Numeric datatypes can be converted to other numeric datatypes or to character datatypes, but they cannot be converted to binary or date datatypes.
Additional guidelines:
All numeric conversions use rounding.
Any loss of digits to the left of the decimal results in an error. For example, an integer of value 123 cannot be converted to a decimal (4,2) value without losing a digit to the left of the decimal point.
Any loss of digits to the right of the decimal point is not considered an error. For example, a float of value 123.456 is converted to an integer of value 123 without an error.
When you transfer data from a decimal column to a float column, the precision of the result is not better than the precision of the target column.
For example, if you transfer data from a decimal(15,0) column to a float column, then back to a decimal(15,0) column, the results in the target decimal(15,0) column do not match the results of the source decimal(15,0) column, due to the float column precision.