Is There a Rounddown() Function in Sql as There Is in Excel

There's a FLOOR function, which can be adapted to your use case:

SELECT FLOOR(value * 100) / 100 AS RoundedValue

You can use TRUNCATE () for this rounddown

select TRUNCATE(2.847, 2) as rounddown

or

SELECT Floor(135.675); //for integer rounding, like 135

You can also use

select round(123.456, 2, 1) as rounddown

The 3rd parameter being non-zero will cause a truncation after the number of decimal points specified in the 2nd parameter.

DB Fiddle

The solution to the problem is to truncate the extra decimal which can be achieved by using the extra parameter of the ROUND function which is ROUND(number, decimal_places, 0/1). Here if the last parameter is anything other than 0, it will truncate the rather than rounding off which is equivalent to the ROUNDDOWN() function of excel that I was looking for.

Alternatively, you can use the TRUNCATE() function, passing the number of decimal places to keep as the second parameter, which will drop off any extra decimals, acting as a ROUNDDOWN() function.

I hope this rounding utility helps somebody:

CREATE FUNCTION `get_round`(val DOUBLE, nDigits INT, RoundStyle VARCHAR(255)) RETURNS double
        NO SQL
    BEGIN
      DECLARE a DOUBLE DEFAULT 0;
      SET nDigits = ifnull(nDigits, 0);

    CASE
        WHEN UCASE(RoundStyle) IN ('ROUND NEAREST','', 'NEAREST', '', 'RND','ROUND', 'DEFAULT','DFLT', null) THEN #normal rounding, but up from 10.50#
                    SET a = round(val, nDigits); 
        WHEN UCASE(RoundStyle) IN('ROUND UP', 'UP') THEN #ROUND 10.554 to 10.56
                    SET a =  ceil(val * (power(10, nDigits) )) / (power(10, nDigits));
        WHEN UCASE(RoundStyle) IN('ROUND DOWN', 'DOWN') THEN #ROUND 10.555 to 10.55
                    SET a =  truncate(val, nDigits) ;                 
        WHEN UCASE(RoundStyle) IN('ROUND BANKER', 'BANKER','BANKERS ROUNDING') THEN #ROUND TO THE NEAREST EVEN 10.555 is 10.56 and 10.565 is 10.56
                    SET a = IF(ABS(val - TRUNCATE(val, nDigits)) * POWER(10, nDigits + 1) = 5 
                            AND NOT CONVERT(TRUNCATE(ABS(val) * POWER(10, nDigits), 0), UNSIGNED) % 2 = 1,
                            TRUNCATE(val, nDigits), ROUND(val, nDigits));
        WHEN UCASE(RoundStyle) IN('ROUND UP INTEGER', 'INT UP','UP INT') THEN #10.4 rounds to 11.0
                    SET a =  ceiling(val);
        WHEN UCASE(RoundStyle) IN('ROUND DOWN INTEGER', 'INT DOWN','DOWN INT') THEN #10.6 rounds to 10.0
                    SET a =  floor(val);
    END CASE;

    RETURN ifnull(a, 0);
    END