Mathematical operators are provided for many PostgreSQL types. For types without common mathematical conventions for all possible permutations (e.g., date/time types) we describe the actual behavior in subsequent sections.
Table 6-2 shows the available mathematical operators.
Table 6-2. Mathematical Operators
Name | Description | Example | Result |
---|---|---|---|
+ | addition | 2 + 3 | 5 |
- | subtraction | 2 - 3 | -1 |
* | multiplication | 2 * 3 | 6 |
/ | division (integer division truncates results) | 4 / 2 | 2 |
% | modulo (remainder) | 5 % 4 | 1 |
^ | exponentiation | 2.0 ^ 3.0 | 8 |
|/ | square root | |/ 25.0 | 5 |
||/ | cube root | ||/ 27.0 | 3 |
! | factorial | 5 ! | 120 |
!! | factorial (prefix operator) | !! 5 | 120 |
@ | absolute value | @ -5.0 | 5 |
& | binary AND | 91 & 15 | 11 |
| | binary OR | 32 | 3 | 35 |
# | binary XOR | 17 # 5 | 20 |
~ | binary NOT | ~1 | -2 |
<< | binary shift left | 1 << 4 | 16 |
>> | binary shift right | 8 >> 2 | 2 |
The "binary" operators are also available for the bit string types BIT and BIT VARYING, as shown in Table 6-3. Bit string arguments to &, |, and # must be of equal length. When bit shifting, the original length of the string is preserved, as shown in the table.
Table 6-3. Bit String Binary Operators
Example | Result |
---|---|
B'10001' & B'01101' | 00001 |
B'10001' | B'01101' | 11101 |
B'10001' # B'01101' | 11110 |
~ B'10001' | 01110 |
B'10001' << 3 | 01000 |
B'10001' >> 2 | 00100 |
Table 6-4 shows the available mathematical functions. In the table, dp indicates double precision. The functions exp, ln, log, pow, round (1 argument), sqrt, and trunc (1 argument) are also available for the type numeric in place of double precision. Functions returning a numeric result take numeric input arguments, unless otherwise specified. Many of these functions are implemented on top of the host system's C library; accuracy and behavior in boundary cases could therefore vary depending on the host system.
Table 6-4. Mathematical Functions
Function | Return Type | Description | Example | Result |
---|---|---|---|---|
abs(x) | (same as x) | absolute value | abs(-17.4) | 17.4 |
cbrt(dp) | dp | cube root | cbrt(27.0) | 3 |
ceil(numeric) | numeric | smallest integer not less than argument | ceil(-42.8) | -42 |
degrees(dp) | dp | radians to degrees | degrees(0.5) | 28.6478897565412 |
exp(dp) | dp | exponential | exp(1.0) | 2.71828182845905 |
floor(numeric) | numeric | largest integer not greater than argument | floor(-42.8) | -43 |
ln(dp) | dp | natural logarithm | ln(2.0) | 0.693147180559945 |
log(dp) | dp | base 10 logarithm | log(100.0) | 2 |
log(b numeric, x numeric) | numeric | logarithm to base b | log(2.0, 64.0) | 6.0000000000 |
mod(y, x) | (same as argument types) | remainder of y/x | mod(9,4) | 1 |
pi() | dp | "Pi" constant | pi() | 3.14159265358979 |
pow(e dp, n dp) | dp | raise a number to exponent e | pow(9.0, 3.0) | 729 |
radians(dp) | dp | degrees to radians | radians(45.0) | 0.785398163397448 |
random() | dp | value between 0.0 to 1.0 | random() | |
round(dp) | dp | round to nearest integer | round(42.4) | 42 |
round(v numeric, s integer) | numeric | round to s decimal places | round(42.4382, 2) | 42.44 |
sign(numeric) | numeric | sign of the argument (-1, 0, +1) | sign(-8.4) | -1 |
sqrt(dp) | dp | square root | sqrt(2.0) | 1.4142135623731 |
trunc(dp) | dp | truncate toward zero | trunc(42.8) | 42 |
trunc(numeric, r integer) | numeric | truncate to s decimal places | trunc(42.4382, 2) | 42.43 |
Finally, Table 6-5 shows the available trigonometric functions. All trigonometric functions have arguments and return values of type double precision.