|PostgreSQL 9.5.25 Documentation|
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The money type stores a currency amount with a fixed fractional precision; see Table 8-3. The fractional precision is determined by the database's lc_monetary setting. The range shown in the table assumes there are two fractional digits. Input is accepted in a variety of formats, including integer and floating-point literals, as well as typical currency formatting, such as '$1,000.00'. Output is generally in the latter form but depends on the locale.
Table 8-3. Monetary Types
|money||8 bytes||currency amount||-92233720368547758.08 to +92233720368547758.07|
Since the output of this data type is locale-sensitive, it might not work to load money data into a database that has a different setting of lc_monetary. To avoid problems, before restoring a dump into a new database make sure lc_monetary has the same or equivalent value as in the database that was dumped.
Values of the numeric, int, and bigint data types can be cast to money. Conversion from the real and double precision data types can be done by casting to numeric first, for example:
However, this is not recommended. Floating point numbers should not be used to handle money due to the potential for rounding errors.
A money value can be cast to numeric without loss of precision. Conversion to other types could potentially lose precision, and must also be done in two stages:
Division of a money value by an integer value is performed with truncation of the fractional part towards zero. To get a rounded result, divide by a floating-point value, or cast the money value to numeric before dividing and back to money afterwards. (The latter is preferable to avoid risking precision loss.) When a money value is divided by another money value, the result is double precision (i.e., a pure number, not money); the currency units cancel each other out in the division.