The real and double precision types are built on types supplied by the operating system. The float type accepts an optional binary precision in parentheses. float columns with a precision of 1–15 are stored as real; those with higher precision are stored as double precision.
The range and storage precision for all three types is machine dependent.
Table 1-10 shows the range and storage size for each approximate numeric type. Note that isql displays only 6 significant digits after the decimal point and rounds the remainder:
Datatype |
Bytes of storage |
|---|---|
float[(default precision)] |
4 for default precision < 16 8 for default precision >= 16 |
double precision |
8 |
real |
4 |
