Packing Codes for Numeric Data
The Uniface Numeric and Float data types are associated with many packing codes.
The following tables show the default packing codes for numeric data types, and the complete list of all packing codes for numeric data. Any packing code may be converted to a more optimum storage format by the DBMS connector. For more information, see the relevant connector documentation.
| Uniface Data Type | Default Packing Code |
|---|---|
| Float | F |
| Numeric | C20 |
| Uniface Packing Code | Explanation | Uniface Data Types | Scaling Allowed | |
|---|---|---|---|---|
| Numeric | Float | |||
| C (C20), C1-C32 | Number, stored sign left, right-aligned, decimal point included, to a maximum of 9 decimal places | Y | Y | Y |
| F | F is mapped to a default of C20 | Y | Y | Y |
| F4 | Single precision F-float | Y | Y | Y |
| F8 | Double-precision D-float | Y | Y | Y |
| G8 | VMS private G-format | Y | Y | |
| H4 | IEEE 4-byte float | Y | Y | Y |
| H8 | IEEE 8-byte float | Y | Y | Y |
| I(12) | Integer | Y | Y | |
| I1 | 1-byte integer | Y | Y | |
| I2 | 2-byte integer | Y | Y | |
| I3 | 3-byte integer | Y | Y | |
| I4 | 4-byte integer | Y | Y | |
| I8 | 8-byte integer | Y | Y | |
| I16 | 16-byte integer | Y | Y | |
| M1 | Money: 8-byte integer | Y | Implicit | |
| M2 | Money: double-precision floating point storage | Y | Implicit | |
| M4 | Sybase internal money data type | Y | Implicit | |
| M6 | Sybase small money format | Y | Implicit | |
| N (N20), N1-N32 | Number, stored without decimal point | Y | Y | |
| O (O20), O1-O32 | Zoned numeric encoding of OpenVMS VAX trailing numeric | Y | ||
| P (P4), P1-P8 | Packed decimal, +/- at beginning of field | Y | Y | |
| Q (Q4), Q1-Q8 | Packed decimal, +/- at end of field | Y | Y | |
| Y1-Y32 | User-defined packing code | Y | ||
Null Values
When data is stored in a DBMS that does not
support NULL values, it is not possible to tell the difference between a value of zero and empty
(NULL) in numeric fields with packing codes I, F, P, and Q. Record-level DBMSs usually do not
support NULL values. If a field with one of these packing codes explicitly receives a value of 0,
Uniface displays it as if the field were empty.
Scaling
If scaling is defined for the packing codes I, F, P, and Q, this is not recognized by the DBMS. The scaling determines a default field layout and how
Uniface handles the data. Other software does not understand scaling with data packed in this way
unless explicitly programmed to do so.
For example, a field that has been defined as
data type Numeric with a packing code of I4.2 (a 4-byte integer with two digits right of the
decimal point) could accept a value of 123.45 within Uniface. The data would be displayed as 123.45 but stored as
12345; only Uniface would know where the decimal point should be.
Uniface Precision—data type Numeric
The I, P, and Q packing codes are internally
equal to Uniface floating point precision—a platform-independent precision of 38 digits
for the mantissa, plus one for rounding, and four digits for the exponent, as follows:
+/- (99,999,999,999,999,999,999,999,999,999,999,999,999e+/- 9999)
The N and O packing codes are represented
internally as a number of digits, of which the maximum is 32, not 38. Therefore, if you want
greater precision than 32 digits, you should select an I, P, or Q packing code. When storing data,
it depends on the DBMS whether this high precision is supported.
Uniface Precision—data type Float
For the data type Float, Uniface internally supports a platform-independent precision of 38 digits for the mantissa, plus one for rounding, and four digits for the exponent, as follows:
+/- (99,999,999,999,999,999,999,999,999,999,999,999,999e+/- 9999)
When storing data, it depends on the DBMS whether this high precision is supported.
User-Defined Packing Codes
You can define your own packing codes for Numeric fields. To do this, you must define the 3GL format conversion routines required by Uniface.
