mariadb-numeric-functions

Use the DIV operator for integer division in MariaDB, which discards the remainder and returns a BIGINT-based integer. The / operator always returns a decimal, so 7/2 gives 3.5000 while 7 DIV 2 gives 3.

ROUND in MariaDB rounds half away from zero for DECIMAL and exact values, so ROUND(2.5) returns 3 and ROUND(-2.5) returns -3. For FLOAT and DOUBLE, the platform C library decides, so results can vary between operating systems.

Division by zero in MariaDB returns NULL by default rather than raising an error. An error occurs only when ERROR_ON_DIVISION_BY_ZERO is enabled in sql_mode, which is part of the default strict mode. The same applies to MOD with a zero divisor.

Use DECIMAL(p,s) for currency and anything needing exactness, since FLOAT and DOUBLE are approximate types where 0.1 + 0.2 does not equal 0.3. DECIMAL supports up to 38 digits of precision.

RAND() is not cryptographically secure and should not be used for security tokens. RAND(N) with a constant seed is repeatable, which suits tests but not secrets, and RAND() is unsafe for statement-based replication.

TRUNCATE(X, D) is a numeric function that chops a number to D decimal places toward zero, while TRUNCATE TABLE is a DDL statement that empties a table. Despite the shared name, the two are unrelated.