Arithmetic operators

seekdb supports commonly used arithmetic operators.

Overview of arithmetic operators

The following table describes the arithmetic operators supported in the current version of seekdb.

Operator	Operand Type	Description
+	Unary/Binary	Unary indicates a positive number, and binary indicates addition.
-	Unary/Binary	Unary indicates a negative number, and binary indicates subtraction.
*	Binary	Multiplication.
/	Binary	Division.
DIV	Binary	Integer division, which returns the quotient.
MOD or %	Binary	Integer division, which returns the remainder. N % M or N MOD M returns the remainder after N is divided by M.

Syntax

Rules for arithmetic operations

The following rules apply to integer division:

• The quotient is rounded to the nearest integer toward zero.

• The sign of the remainder is the same as the sign of the dividend.

Here is an example:

SELECT (-7) DIV (3.6), (-7) MOD (3.6);
+----------------+----------------+
| (-7) DIV (3.6) | (-7) MOD (3.6) |
+----------------+----------------+
|             -1 |           -3.4 |
+----------------+----------------+
1 row in set (0.001 sec)

SELECT (-7) DIV (-3.4), (-7) % (-3.4);
+-----------------+---------------+
| (-7) DIV (-3.4) | (-7) % (-3.4) |
+-----------------+---------------+
|               2 |          -0.2 |
+-----------------+---------------+
1 row in set (0.001 sec)

Results of arithmetic operations

The result of an arithmetic operation is determined based on the following rules:

• For the operators -, +, and *, if both operands are integers, the result is calculated with BIGINT (64-bit) precision.

• If both operands are integers and one of them is an unsigned integer, the result is an unsigned integer. However, if the NO_UNSIGNED_SUBTRACTION SQL mode is enabled, the result of a subtraction operation is signed even if one of the operands is an unsigned integer.

• If the operands of +, -, /, *, or % are real numbers or string values, the result has the precision of the operand with the highest precision.

• When you use the / operator to divide two exact-value operands, the number of decimal places in the result is the number of decimal places in the first operand plus the value of the div_precision_increment system variable (default value is 4). For example, the expression 5.15/0.013 has six decimal places (396.153846).